<!-- Generated by iC(tm) - CompSci Interactive Converter - http://www.compsciresources.com -->
<!-- Created: Wed May 08 23:16:16 UTC 2013 -->
<linkbase xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:xbrldt="http://xbrl.org/2005/xbrldt">
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_ConsolidatedBalanceSheet" roleURI="http://www.celsion.com/role/ConsolidatedBalanceSheet"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_ConsolidatedBalanceSheet_Parentheticals" roleURI="http://www.celsion.com/role/ConsolidatedBalanceSheet_Parentheticals"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_ConsolidatedIncomeStatement" roleURI="http://www.celsion.com/role/ConsolidatedIncomeStatement"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_ConsolidatedComprehensiveIncome" roleURI="http://www.celsion.com/role/ConsolidatedComprehensiveIncome"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_ConsolidatedCashFlow" roleURI="http://www.celsion.com/role/ConsolidatedCashFlow"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_Note" roleURI="http://www.celsion.com/role/Note"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_Note0" roleURI="http://www.celsion.com/role/Note0"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_Note00" roleURI="http://www.celsion.com/role/Note00"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_Note000" roleURI="http://www.celsion.com/role/Note000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_Note0000" roleURI="http://www.celsion.com/role/Note0000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_Note00000" roleURI="http://www.celsion.com/role/Note00000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_Note000000" roleURI="http://www.celsion.com/role/Note000000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_Note0000000" roleURI="http://www.celsion.com/role/Note0000000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_Note00000000" roleURI="http://www.celsion.com/role/Note00000000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_Note000000000" roleURI="http://www.celsion.com/role/Note000000000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_Note0000000000" roleURI="http://www.celsion.com/role/Note0000000000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_Note00000000000" roleURI="http://www.celsion.com/role/Note00000000000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_Note000000000000" roleURI="http://www.celsion.com/role/Note000000000000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_AccountingPoliciesByPolicy" roleURI="http://www.celsion.com/role/AccountingPoliciesByPolicy"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_NoteTables" roleURI="http://www.celsion.com/role/NoteTables"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_NoteTables0" roleURI="http://www.celsion.com/role/NoteTables0"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_NoteTables00" roleURI="http://www.celsion.com/role/NoteTables00"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_NoteTables000" roleURI="http://www.celsion.com/role/NoteTables000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_NoteTables0000" roleURI="http://www.celsion.com/role/NoteTables0000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_NoteTables00000" roleURI="http://www.celsion.com/role/NoteTables00000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_NoteTables000000" roleURI="http://www.celsion.com/role/NoteTables000000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_ShorttermInvestmentbyBondMaturitiesTable" roleURI="http://www.celsion.com/role/ShorttermInvestmentbyBondMaturitiesTable"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_ShorttermInvestmentContinuousUnrealizedLossPositionTable" roleURI="http://www.celsion.com/role/ShorttermInvestmentContinuousUnrealizedLossPositionTable"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_InvestmentIncomeTable" roleURI="http://www.celsion.com/role/InvestmentIncomeTable"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_AssetsandLiabilitiesatFairValueonaRecurringBasisTable" roleURI="http://www.celsion.com/role/AssetsandLiabilitiesatFairValueonaRecurringBasisTable"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_OtherAccruedLiabilitiesTable" roleURI="http://www.celsion.com/role/OtherAccruedLiabilitiesTable"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_FuturePrincipalPaymentsDueontheCreditAgreementTable" roleURI="http://www.celsion.com/role/FuturePrincipalPaymentsDueontheCreditAgreementTable"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_AssumptionsforvaluationofthewarrantsissuedinPreferredStockOfferingTable" roleURI="http://www.celsion.com/role/AssumptionsforvaluationofthewarrantsissuedinPreferredStockOfferingTable"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_FairValueofOptionAssumptionsTable" roleURI="http://www.celsion.com/role/FairValueofOptionAssumptionsTable"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_StockOptionandRestrictedStockAwardsTable" roleURI="http://www.celsion.com/role/StockOptionandRestrictedStockAwardsTable"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_SummaryofWarrantActivityTable" roleURI="http://www.celsion.com/role/SummaryofWarrantActivityTable"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_FairValueofWarrantsAssumptionsTable" roleURI="http://www.celsion.com/role/FairValueofWarrantsAssumptionsTable"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_CommonStockWarrantLiabilityTable" roleURI="http://www.celsion.com/role/CommonStockWarrantLiabilityTable"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_NoteDetail" roleURI="http://www.celsion.com/role/NoteDetail"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_NoteDetail0" roleURI="http://www.celsion.com/role/NoteDetail0"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_NoteDetail00" roleURI="http://www.celsion.com/role/NoteDetail00"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_NoteDetail000" roleURI="http://www.celsion.com/role/NoteDetail000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_NoteDetail0000" roleURI="http://www.celsion.com/role/NoteDetail0000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_NoteDetail00000" roleURI="http://www.celsion.com/role/NoteDetail00000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_NoteDetail000000" roleURI="http://www.celsion.com/role/NoteDetail000000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_NoteDetail0000000" roleURI="http://www.celsion.com/role/NoteDetail0000000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_NoteDetail00000000" roleURI="http://www.celsion.com/role/NoteDetail00000000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_NoteDetail000000000" roleURI="http://www.celsion.com/role/NoteDetail000000000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_NoteDetail0000000000" roleURI="http://www.celsion.com/role/NoteDetail0000000000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#clsn_NoteDetail00000000000" roleURI="http://www.celsion.com/role/NoteDetail00000000000"/>
  <roleRef xlink:type="simple" xlink:href="clsn-20130331.xsd#DocumentAndEntityInformation" roleURI="http://www.celsion.com/role/DocumentAndEntityInformation"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" arcroleURI="http://xbrl.org/int/dim/arcrole/all"/>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/ConsolidatedBalanceSheet">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AssetsAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AssetsAbstract"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_AssetsAbstract" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_CurrentAssetsAbstract" xlink:href="clsn-20130331.xsd#clsn_CurrentAssetsAbstract"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsAbstract" xlink:to="clsn_CurrentAssetsAbstract" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CurrentAssetsAbstract" xlink:to="us-gaap_CashAndCashEquivalentsAtCarryingValue" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShortTermInvestments" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShortTermInvestments"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CurrentAssetsAbstract" xlink:to="us-gaap_ShortTermInvestments" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AccruedInvestmentIncomeReceivable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AccruedInvestmentIncomeReceivable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CurrentAssetsAbstract" xlink:to="us-gaap_AccruedInvestmentIncomeReceivable" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_GrantsReceivableCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_GrantsReceivableCurrent"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CurrentAssetsAbstract" xlink:to="us-gaap_GrantsReceivableCurrent" order="3" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CurrentAssetsAbstract" xlink:to="us-gaap_PrepaidExpenseAndOtherAssetsCurrent" order="4" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AssetsCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AssetsCurrent"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:to="us-gaap_AssetsCurrent" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PropertyPlantAndEquipmentNet" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsAbstract" xlink:to="us-gaap_PropertyPlantAndEquipmentNet" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherAssetsAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OtherAssetsAbstract"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AssetsAbstract" xlink:to="us-gaap_OtherAssetsAbstract" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DepositsAssetsNoncurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DepositsAssetsNoncurrent"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherAssetsAbstract" xlink:to="us-gaap_DepositsAssetsNoncurrent" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherAssetsAbstract" xlink:to="us-gaap_FiniteLivedIntangibleAssetsNet" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AssetsNoncurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AssetsNoncurrent"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:to="us-gaap_AssetsNoncurrent" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_Assets" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_Assets"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:to="us-gaap_Assets" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_LiabilitiesAndStockholdersEquityAbstract" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_CurrentLiabilitiesAbstract" xlink:href="clsn-20130331.xsd#clsn_CurrentLiabilitiesAbstract"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:to="clsn_CurrentLiabilitiesAbstract" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AccountsPayableCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AccountsPayableCurrent"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CurrentLiabilitiesAbstract" xlink:to="us-gaap_AccountsPayableCurrent" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherAccruedLiabilitiesCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OtherAccruedLiabilitiesCurrent"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CurrentLiabilitiesAbstract" xlink:to="us-gaap_OtherAccruedLiabilitiesCurrent" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NotesPayableCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NotesPayableCurrent"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CurrentLiabilitiesAbstract" xlink:to="us-gaap_NotesPayableCurrent" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredRevenueCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredRevenueCurrent"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CurrentLiabilitiesAbstract" xlink:to="us-gaap_DeferredRevenueCurrent" order="3" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LiabilitiesCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LiabilitiesCurrent"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DeferredRevenueCurrent" xlink:to="us-gaap_LiabilitiesCurrent" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_CommonStockWarrantLiability" xlink:href="clsn-20130331.xsd#clsn_CommonStockWarrantLiability"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CurrentLiabilitiesAbstract" xlink:to="clsn_CommonStockWarrantLiability" order="4" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LongTermNotesPayable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LongTermNotesPayable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CurrentLiabilitiesAbstract" xlink:to="us-gaap_LongTermNotesPayable" order="5" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredRevenueNoncurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredRevenueNoncurrent"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CurrentLiabilitiesAbstract" xlink:to="us-gaap_DeferredRevenueNoncurrent" order="6" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherLiabilitiesNoncurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CurrentLiabilitiesAbstract" xlink:to="us-gaap_OtherLiabilitiesNoncurrent" order="7" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_Liabilities" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_Liabilities"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherLiabilitiesNoncurrent" xlink:to="us-gaap_Liabilities" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockholdersEquityAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockholdersEquityAbstract"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:to="us-gaap_StockholdersEquityAbstract" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PreferredStockValue" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PreferredStockValue"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="us-gaap_PreferredStockValue" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CommonStockValueOutstanding" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CommonStockValueOutstanding"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="us-gaap_CommonStockValueOutstanding" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AdditionalPaidInCapitalCommonStock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AdditionalPaidInCapitalCommonStock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="us-gaap_AdditionalPaidInCapitalCommonStock" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" order="3" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="us-gaap_RetainedEarningsAccumulatedDeficit" order="4" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockholdersEquityBeforeTreasuryStock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockholdersEquityBeforeTreasuryStock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RetainedEarningsAccumulatedDeficit" xlink:to="us-gaap_StockholdersEquityBeforeTreasuryStock" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_TreasuryStockValue" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_TreasuryStockValue"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="us-gaap_TreasuryStockValue" order="5" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockholdersEquity" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockholdersEquity"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TreasuryStockValue" xlink:to="us-gaap_StockholdersEquity" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_TreasuryStockValue" xlink:to="us-gaap_LiabilitiesAndStockholdersEquity" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/ConsolidatedBalanceSheet_Parentheticals">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PreferredStockParOrStatedValuePerShare" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PreferredStockParOrStatedValuePerShare"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PreferredStockParOrStatedValuePerShare" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PreferredStockSharesAuthorized" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PreferredStockSharesAuthorized"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PreferredStockSharesAuthorized" order="3" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PreferredStockSharesIssued" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PreferredStockSharesIssued"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PreferredStockSharesIssued" order="4" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PreferredStockSharesOutstanding" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PreferredStockSharesOutstanding"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PreferredStockSharesOutstanding" order="5" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockParOrStatedValuePerShare" order="6" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CommonStockSharesAuthorized" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockSharesAuthorized" order="7" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CommonStockSharesIssued" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CommonStockSharesIssued"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockSharesIssued" order="8" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CommonStockSharesOutstanding" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockSharesOutstanding" order="9" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_TreasuryStockShares" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_TreasuryStockShares"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_TreasuryStockShares" order="10" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/ConsolidatedIncomeStatement">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LicensesRevenue" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LicensesRevenue"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_LicensesRevenue" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OperatingExpensesAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OperatingExpensesAbstract"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_OperatingExpensesAbstract" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ResearchAndDevelopmentExpense" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingExpensesAbstract" xlink:to="us-gaap_ResearchAndDevelopmentExpense" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_GeneralAndAdministrativeExpense" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OperatingExpensesAbstract" xlink:to="us-gaap_GeneralAndAdministrativeExpense" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OperatingExpenses" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OperatingExpenses"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_GeneralAndAdministrativeExpense" xlink:to="us-gaap_OperatingExpenses" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OperatingIncomeLoss" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OperatingIncomeLoss"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_OperatingIncomeLoss" order="3" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_OtherIncomeExpenseAbstract" xlink:href="clsn-20130331.xsd#clsn_OtherIncomeExpenseAbstract"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_OtherIncomeExpenseAbstract" order="4" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_GainlossfromchangeinValuationofCommonStockWarrantLiability" xlink:href="clsn-20130331.xsd#clsn_GainlossfromchangeinValuationofCommonStockWarrantLiability"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_OtherIncomeExpenseAbstract" xlink:to="clsn_GainlossfromchangeinValuationofCommonStockWarrantLiability" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_InvestmentIncomeInterest" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_InvestmentIncomeInterest"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_OtherIncomeExpenseAbstract" xlink:to="us-gaap_InvestmentIncomeInterest" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_InterestAndDebtExpense" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_InterestAndDebtExpense"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_OtherIncomeExpenseAbstract" xlink:to="us-gaap_InterestAndDebtExpense" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NonoperatingIncomeExpense" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_InterestAndDebtExpense" xlink:to="us-gaap_NonoperatingIncomeExpense" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NetIncomeLoss" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_NetIncomeLoss" order="5" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherPreferredStockDividendsAndAdjustments" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OtherPreferredStockDividendsAndAdjustments"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_NetIncomeLoss" xlink:to="us-gaap_OtherPreferredStockDividendsAndAdjustments" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" order="6" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_EarningsPerShareBasicAndDiluted" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EarningsPerShareBasicAndDiluted"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_EarningsPerShareBasicAndDiluted" order="7" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_WeightedAverageNumberOfShareOutstandingBasicAndDiluted" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_WeightedAverageNumberOfShareOutstandingBasicAndDiluted"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_WeightedAverageNumberOfShareOutstandingBasicAndDiluted" order="8" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/ConsolidatedComprehensiveIncome">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_BalanceSheetLocationAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_BalanceSheetLocationAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_BalanceSheetLocationDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_BalanceSheetLocationAxis" xlink:to="us-gaap_BalanceSheetLocationDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_BalanceSheetLocationDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_BalanceSheetLocationAxis" xlink:to="us-gaap_BalanceSheetLocationDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_OtherIncomeNetMember" xlink:href="clsn-20130331.xsd#clsn_OtherIncomeNetMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_BalanceSheetLocationDomain" xlink:to="clsn_OtherIncomeNetMember" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_OtherComprehensiveLossAbstract" xlink:href="clsn-20130331.xsd#clsn_OtherComprehensiveLossAbstract"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_OtherComprehensiveLossAbstract" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_ChangesInAbstract" xlink:href="clsn-20130331.xsd#clsn_ChangesInAbstract"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_OtherComprehensiveLossAbstract" xlink:to="clsn_ChangesInAbstract" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentForSaleOfSecuritiesIncludedInNetIncomeBeforeTax" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentForSaleOfSecuritiesIncludedInNetIncomeBeforeTax"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_ChangesInAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentForSaleOfSecuritiesIncludedInNetIncomeBeforeTax" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_ChangesInAbstract" xlink:to="us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_ChangesInAbstract" xlink:to="us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NetIncomeLoss" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_OtherComprehensiveLossAbstract" xlink:to="us-gaap_NetIncomeLoss" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ComprehensiveIncomeNetOfTax" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTax"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ComprehensiveIncomeNetOfTax" order="2" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/ConsolidatedCashFlow">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:to="us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:to="us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_CommonStockWarrantsMember" xlink:href="clsn-20130331.xsd#clsn_CommonStockWarrantsMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:to="clsn_CommonStockWarrantsMember" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_CashFlowsFromOperatingActivitiesAbstract" xlink:href="clsn-20130331.xsd#clsn_CashFlowsFromOperatingActivitiesAbstract"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_CashFlowsFromOperatingActivitiesAbstract" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NetIncomeLoss" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CashFlowsFromOperatingActivitiesAbstract" xlink:to="us-gaap_NetIncomeLoss" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_NonCashItemsIncludedInNetIncomeLossAbstract" xlink:href="clsn-20130331.xsd#clsn_NonCashItemsIncludedInNetIncomeLossAbstract"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CashFlowsFromOperatingActivitiesAbstract" xlink:to="clsn_NonCashItemsIncludedInNetIncomeLossAbstract" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DepreciationDepletionAndAmortization" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_NonCashItemsIncludedInNetIncomeLossAbstract" xlink:to="us-gaap_DepreciationDepletionAndAmortization" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_ChangeInFairValueOfCommonStockWarrantLiability" xlink:href="clsn-20130331.xsd#clsn_ChangeInFairValueOfCommonStockWarrantLiability"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_NonCashItemsIncludedInNetIncomeLossAbstract" xlink:to="clsn_ChangeInFairValueOfCommonStockWarrantLiability" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInDeferredRevenue" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncreaseDecreaseInDeferredRevenue"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_NonCashItemsIncludedInNetIncomeLossAbstract" xlink:to="us-gaap_IncreaseDecreaseInDeferredRevenue" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensation" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensation"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_NonCashItemsIncludedInNetIncomeLossAbstract" xlink:to="us-gaap_ShareBasedCompensation" order="3" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_TreasuryStockContributedTo401KPlan" xlink:href="clsn-20130331.xsd#clsn_TreasuryStockContributedTo401KPlan"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_NonCashItemsIncludedInNetIncomeLossAbstract" xlink:to="clsn_TreasuryStockContributedTo401KPlan" order="4" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherAmortizationOfDeferredCharges" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OtherAmortizationOfDeferredCharges"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_NonCashItemsIncludedInNetIncomeLossAbstract" xlink:to="us-gaap_OtherAmortizationOfDeferredCharges" order="5" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_NetChangesInAbstract" xlink:href="clsn-20130331.xsd#clsn_NetChangesInAbstract"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_NonCashItemsIncludedInNetIncomeLossAbstract" xlink:to="clsn_NetChangesInAbstract" order="6" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInAccruedInvestmentIncomeReceivable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncreaseDecreaseInAccruedInvestmentIncomeReceivable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_NetChangesInAbstract" xlink:to="us-gaap_IncreaseDecreaseInAccruedInvestmentIncomeReceivable" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_NetChangesInAbstract" xlink:to="us-gaap_IncreaseDecreaseInAccountsPayable" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInOtherAccruedLiabilities" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncreaseDecreaseInOtherAccruedLiabilities"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_NetChangesInAbstract" xlink:to="us-gaap_IncreaseDecreaseInOtherAccruedLiabilities" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_IncreaseDecreaseInOtherAccruedLiabilities" xlink:to="us-gaap_NetCashProvidedByUsedInOperatingActivities" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_CashFlowsFromInvestingActivitiesAbstract" xlink:href="clsn-20130331.xsd#clsn_CashFlowsFromInvestingActivitiesAbstract"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_CashFlowsFromInvestingActivitiesAbstract" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquireAvailableForSaleSecurities" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PaymentsToAcquireAvailableForSaleSecurities"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CashFlowsFromInvestingActivitiesAbstract" xlink:to="us-gaap_PaymentsToAcquireAvailableForSaleSecurities" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CashFlowsFromInvestingActivitiesAbstract" xlink:to="us-gaap_ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CashFlowsFromInvestingActivitiesAbstract" xlink:to="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivities" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_CashFlowsFromFinancingActivitiesAbstract" xlink:href="clsn-20130331.xsd#clsn_CashFlowsFromFinancingActivitiesAbstract"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_CashFlowsFromFinancingActivitiesAbstract" order="3" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromIssuanceOfRedeemableConvertiblePreferredStock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ProceedsFromIssuanceOfRedeemableConvertiblePreferredStock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CashFlowsFromFinancingActivitiesAbstract" xlink:to="us-gaap_ProceedsFromIssuanceOfRedeemableConvertiblePreferredStock" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CashFlowsFromFinancingActivitiesAbstract" xlink:to="us-gaap_ProceedsFromIssuanceOfCommonStock" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromWarrantExercises" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ProceedsFromWarrantExercises"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CashFlowsFromFinancingActivitiesAbstract" xlink:to="us-gaap_ProceedsFromWarrantExercises" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromStockOptionsExercised" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ProceedsFromStockOptionsExercised"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CashFlowsFromFinancingActivitiesAbstract" xlink:to="us-gaap_ProceedsFromStockOptionsExercised" order="3" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_RepaymentsOfNotesPayable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RepaymentsOfNotesPayable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CashFlowsFromFinancingActivitiesAbstract" xlink:to="us-gaap_RepaymentsOfNotesPayable" order="4" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RepaymentsOfNotesPayable" xlink:to="us-gaap_NetCashProvidedByUsedInFinancingActivities" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" order="4" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CashAndCashEquivalentsAtCarryingValue" order="5" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_SupplementalDisclosuresOfCashFlowInformationAbstract" xlink:href="clsn-20130331.xsd#clsn_SupplementalDisclosuresOfCashFlowInformationAbstract"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_SupplementalDisclosuresOfCashFlowInformationAbstract" order="6" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DividendsAndInterestPaid" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DividendsAndInterestPaid"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_SupplementalDisclosuresOfCashFlowInformationAbstract" xlink:to="us-gaap_DividendsAndInterestPaid" order="0" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/Note">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NatureOfOperations" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NatureOfOperations"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_NatureOfOperations" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/Note0">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_BasisOfPresentationAndSignificantAccountingPoliciesTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BasisOfPresentationAndSignificantAccountingPoliciesTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_BasisOfPresentationAndSignificantAccountingPoliciesTextBlock" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/Note00">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DescriptionOfNewAccountingPronouncementsNotYetAdopted" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DescriptionOfNewAccountingPronouncementsNotYetAdopted"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_DescriptionOfNewAccountingPronouncementsNotYetAdopted" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/Note000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_EarningsPerShareTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EarningsPerShareTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_EarningsPerShareTextBlock" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/Note0000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/Note00000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueDisclosuresTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueDisclosuresTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_FairValueDisclosuresTextBlock" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/Note000000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/Note0000000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DebtDisclosureTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DebtDisclosureTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_DebtDisclosureTextBlock" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/Note00000000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockholdersEquityNoteDisclosureTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockholdersEquityNoteDisclosureTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockholdersEquityNoteDisclosureTextBlock" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/Note000000000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/Note0000000000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_WarrantsTextBlock" xlink:href="clsn-20130331.xsd#clsn_WarrantsTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_WarrantsTextBlock" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/Note00000000000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CommitmentsAndContingenciesDisclosureTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/Note000000000000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_LicensingTransactionTextBlock" xlink:href="clsn-20130331.xsd#clsn_LicensingTransactionTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_LicensingTransactionTextBlock" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/AccountingPoliciesByPolicy">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_BusinessDescriptionAndBasisOfPresentationTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BusinessDescriptionAndBasisOfPresentationTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_BusinessDescriptionAndBasisOfPresentationTextBlock" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_BasisOfAccountingPolicyPolicyTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_BasisOfAccountingPolicyPolicyTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_BasisOfAccountingPolicyPolicyTextBlock" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock" order="3" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/NoteTables">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AvailableForSaleSecuritiesTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AvailableForSaleSecuritiesTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_AvailableForSaleSecuritiesTextBlock" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueTableTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueTableTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueTableTextBlock" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_InvestmentIncomeTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_InvestmentIncomeTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_InvestmentIncomeTextBlock" order="3" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/NoteTables0">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ScheduleOfFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTableTextBlock" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/NoteTables00">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/NoteTables000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/NoteTables0000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/NoteTables00000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfShareBasedPaymentAwardEmployeeStockPurchasePlanValuationAssumptionsTableTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfShareBasedPaymentAwardEmployeeStockPurchasePlanValuationAssumptionsTableTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ScheduleOfShareBasedPaymentAwardEmployeeStockPurchasePlanValuationAssumptionsTableTextBlock" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_ScheduleOfShareBasedCompensationStockOptionsAndRestrictedStockAwardsActivityTableTextBlock" xlink:href="clsn-20130331.xsd#clsn_ScheduleOfShareBasedCompensationStockOptionsAndRestrictedStockAwardsActivityTableTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_ScheduleOfShareBasedCompensationStockOptionsAndRestrictedStockAwardsActivityTableTextBlock" order="2" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/NoteTables000000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_ScheduleOfCommonStockWarrantLiabilityValuationAssumptionsTableTextBlock" xlink:href="clsn-20130331.xsd#clsn_ScheduleOfCommonStockWarrantLiabilityValuationAssumptionsTableTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_ScheduleOfCommonStockWarrantLiabilityValuationAssumptionsTableTextBlock" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_ScheduleOfCommonStockWarrantyLiabilityTableTextBlock" xlink:href="clsn-20130331.xsd#clsn_ScheduleOfCommonStockWarrantyLiabilityTableTextBlock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_ScheduleOfCommonStockWarrantyLiabilityTableTextBlock" order="3" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/ShorttermInvestmentbyBondMaturitiesTable">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_MaturitiesAxis" xlink:href="clsn-20130331.xsd#clsn_MaturitiesAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="clsn_MaturitiesAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_MaturitiesDomain" xlink:href="clsn-20130331.xsd#clsn_MaturitiesDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="clsn_MaturitiesAxis" xlink:to="clsn_MaturitiesDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_MaturitiesDomain_0" xlink:href="clsn-20130331.xsd#clsn_MaturitiesDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="clsn_MaturitiesAxis" xlink:to="clsn_MaturitiesDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_WithinThreeMonthsMember" xlink:href="clsn-20130331.xsd#clsn_WithinThreeMonthsMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_MaturitiesDomain" xlink:to="clsn_WithinThreeMonthsMember" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_BetweenThreeToTwelveMonthsMember" xlink:href="clsn-20130331.xsd#clsn_BetweenThreeToTwelveMonthsMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_MaturitiesDomain" xlink:to="clsn_BetweenThreeToTwelveMonthsMember" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_BondmaturitiesMember" xlink:href="clsn-20130331.xsd#clsn_BondmaturitiesMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_MaturitiesDomain" xlink:to="clsn_BondmaturitiesMember" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_CorporateBondMaturitiesAbstract" xlink:href="clsn-20130331.xsd#clsn_CorporateBondMaturitiesAbstract"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_CorporateBondMaturitiesAbstract" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CorporateBondMaturitiesAbstract" xlink:to="us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_AvailableForSaleDebtSecuritiesFairValueDisclosure" xlink:href="clsn-20130331.xsd#clsn_AvailableForSaleDebtSecuritiesFairValueDisclosure"/>
<!-- [WMV4][XcpuxYn59dz7vgYynUDuwG7r97K2jUTysl7vcz0lJt8UCLPdYZl35nXbOCDIyGTq5FavqtGjnL5Z5Ll3uOVplOYuQoxtbnKP80BbImih3FGmuj6z9i3y546vy1ByNW3odKPmKOEVLjN8kdosHpe8Qaxu180/Fc8za/rf4YQS1DKsV7Qmnx4wJE9Id3fUZeF1ZPsB6DZ7qGvbMsnkabPAEORfeAkqmAiij9dDG6RoBe6vVsZ/XkVsAQ==] CSR-->
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CorporateBondMaturitiesAbstract" xlink:to="clsn_AvailableForSaleDebtSecuritiesFairValueDisclosure" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/ShorttermInvestmentContinuousUnrealizedLossPositionTable">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:to="us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:to="us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DebtSecuritiesMember" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DebtSecuritiesMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:to="us-gaap_DebtSecuritiesMember" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_AvailableForSaleAbstract" xlink:href="clsn-20130331.xsd#clsn_AvailableForSaleAbstract"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_AvailableForSaleAbstract" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_AvailableForSaleAbstract" xlink:to="us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AvailableforsaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses2" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AvailableforsaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses2"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_AvailableForSaleAbstract" xlink:to="us-gaap_AvailableforsaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses2" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AvailableforsaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses2" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AvailableforsaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses2"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_AvailableForSaleAbstract" xlink:to="us-gaap_AvailableforsaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses2" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_AvailableForSaleAbstract" xlink:to="us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue" order="3" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/InvestmentIncomeTable">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_InvestmentIncomeInterestAndDividend" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_InvestmentIncomeInterestAndDividend"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_InvestmentIncomeInterestAndDividend" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AvailableForSaleSecuritiesGrossRealizedGainLossNet" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AvailableForSaleSecuritiesGrossRealizedGainLossNet"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_AvailableForSaleSecuritiesGrossRealizedGainLossNet" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_RealizedInvestmentGainsLosses" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RealizedInvestmentGainsLosses"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_RealizedInvestmentGainsLosses" order="3" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/AssetsandLiabilitiesatFairValueonaRecurringBasisTable">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:to="us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:to="us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_FairValueByFairValueHierarchyLevelAxis" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:to="us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueInputsLevel1Member" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel1Member" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueInputsLevel2Member" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel2Member" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueInputsLevel3Member" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:to="us-gaap_FairValueInputsLevel3Member" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CorporateDebtSecuritiesMember" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:to="us-gaap_CorporateDebtSecuritiesMember" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_AssetsAbstract0" xlink:href="clsn-20130331.xsd#clsn_AssetsAbstract0"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_AssetsAbstract0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_ShortTermInvestmentsAvailableForSaleAbstract" xlink:href="clsn-20130331.xsd#clsn_ShortTermInvestmentsAvailableForSaleAbstract"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_AssetsAbstract0" xlink:to="clsn_ShortTermInvestmentsAvailableForSaleAbstract" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AvailableForSaleSecuritiesFairValueDisclosure" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AvailableForSaleSecuritiesFairValueDisclosure"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_ShortTermInvestmentsAvailableForSaleAbstract" xlink:to="us-gaap_AvailableForSaleSecuritiesFairValueDisclosure" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_AsOfDecember312012Abstract" xlink:href="clsn-20130331.xsd#clsn_AsOfDecember312012Abstract"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_AssetsAbstract0" xlink:to="clsn_AsOfDecember312012Abstract" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_ShortTermInvestmentsAvailableForSaleAbstract0" xlink:href="clsn-20130331.xsd#clsn_ShortTermInvestmentsAvailableForSaleAbstract0"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_AsOfDecember312012Abstract" xlink:to="clsn_ShortTermInvestmentsAvailableForSaleAbstract0" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LiabilitiesAbstract" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LiabilitiesAbstract"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_LiabilitiesAbstract" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_AsOfMarch312013Abstract" xlink:href="clsn-20130331.xsd#clsn_AsOfMarch312013Abstract"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_LiabilitiesAbstract" xlink:to="clsn_AsOfMarch312013Abstract" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_CommonStockWarrantLiabilityFairValueDisclosure" xlink:href="clsn-20130331.xsd#clsn_CommonStockWarrantLiabilityFairValueDisclosure"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_AsOfMarch312013Abstract" xlink:to="clsn_CommonStockWarrantLiabilityFairValueDisclosure" order="0" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/OtherAccruedLiabilitiesTable">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ContractualObligation" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ContractualObligation"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ContractualObligation" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_EmployeeRelatedLiabilitiesCurrent" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AccruedProfessionalFeesCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AccruedProfessionalFeesCurrent"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_AccruedProfessionalFeesCurrent" order="3" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_OtherAccruedLiabilitiesMiscellaneousCurrent" xlink:href="clsn-20130331.xsd#clsn_OtherAccruedLiabilitiesMiscellaneousCurrent"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_OtherAccruedLiabilitiesMiscellaneousCurrent" order="4" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherAccruedLiabilitiesCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OtherAccruedLiabilitiesCurrent"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_OtherAccruedLiabilitiesCurrent" order="5" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/FuturePrincipalPaymentsDueontheCreditAgreementTable">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive" order="3" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LongTermDebt" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LongTermDebt"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_LongTermDebt" order="4" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/AssumptionsforvaluationofthewarrantsissuedinPreferredStockOfferingTable">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" order="3" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedForfeitureRate" xlink:href="clsn-20130331.xsd#clsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedForfeitureRate"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedForfeitureRate" order="4" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" order="5" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/FairValueofOptionAssumptionsTable">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_RangeAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_RangeAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_RangeAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_RangeDomain" xlink:href="clsn-20130331.xsd#clsn_RangeDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RangeAxis" xlink:to="clsn_RangeDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_RangeDomain_0" xlink:href="clsn-20130331.xsd#clsn_RangeDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_RangeAxis" xlink:to="clsn_RangeDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_MinimumMember" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MinimumMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_RangeDomain" xlink:to="us-gaap_MinimumMember" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" order="3" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedForfeitureRate" xlink:href="clsn-20130331.xsd#clsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedForfeitureRate"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedForfeitureRate" order="4" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" order="5" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/StockOptionandRestrictedStockAwardsTable">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" order="3" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" order="4" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" order="5" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" order="6" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" order="7" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" order="8" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod" order="9" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice" order="10" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_WeightedAverageContractualTermsOfEquityAwardsOutstanding" xlink:href="clsn-20130331.xsd#clsn_WeightedAverageContractualTermsOfEquityAwardsOutstanding"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_WeightedAverageContractualTermsOfEquityAwardsOutstanding" order="11" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityOtherThanOptionsNonvestedOutstandingIntrinsicValue" xlink:href="clsn-20130331.xsd#clsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityOtherThanOptionsNonvestedOutstandingIntrinsicValue"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityOtherThanOptionsNonvestedOutstandingIntrinsicValue" order="12" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" order="13" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" order="14" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_WeightedAverageContractualTermsOfEquityAwardsExercisable" xlink:href="clsn-20130331.xsd#clsn_WeightedAverageContractualTermsOfEquityAwardsExercisable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_WeightedAverageContractualTermsOfEquityAwardsExercisable" order="15" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/SummaryofWarrantActivityTable">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementEquityComponentsAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementEquityComponentsAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_WarrantMember" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_WarrantMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_WarrantMember" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ClassOfWarrantOrRightOutstanding" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ClassOfWarrantOrRightOutstanding"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightOutstanding" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" order="3" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_WarrantsGrantedWeightedAverageExercisePrice" xlink:href="clsn-20130331.xsd#clsn_WarrantsGrantedWeightedAverageExercisePrice"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_WarrantsGrantedWeightedAverageExercisePrice" order="4" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_WarrantsExercisedForCommonStock" xlink:href="clsn-20130331.xsd#clsn_WarrantsExercisedForCommonStock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_WarrantsExercisedForCommonStock" order="5" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_WarrantsExercisedForCommonStockWeightedAverageExercisePrice" xlink:href="clsn-20130331.xsd#clsn_WarrantsExercisedForCommonStockWeightedAverageExercisePrice"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_WarrantsExercisedForCommonStockWeightedAverageExercisePrice" order="6" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms" order="7" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/FairValueofWarrantsAssumptionsTable">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueAssumptionsRiskFreeInterestRate" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueAssumptionsRiskFreeInterestRate"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_FairValueAssumptionsRiskFreeInterestRate" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueAssumptionsExpectedVolatilityRate" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueAssumptionsExpectedVolatilityRate"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_FairValueAssumptionsExpectedVolatilityRate" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueAssumptionsExpectedTerm" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueAssumptionsExpectedTerm"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_FairValueAssumptionsExpectedTerm" order="3" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_FairValueAssumptionsExpectedForfeitureRate" xlink:href="clsn-20130331.xsd#clsn_FairValueAssumptionsExpectedForfeitureRate"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_FairValueAssumptionsExpectedForfeitureRate" order="4" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueAssumptionsExpectedDividendRate" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueAssumptionsExpectedDividendRate"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_FairValueAssumptionsExpectedDividendRate" order="5" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/CommonStockWarrantLiabilityTable">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_CommonStockWarrantLiability" xlink:href="clsn-20130331.xsd#clsn_CommonStockWarrantLiability"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_CommonStockWarrantLiability" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_ChangeInFairValueOfCommonStockWarrantLiability" xlink:href="clsn-20130331.xsd#clsn_ChangeInFairValueOfCommonStockWarrantLiability"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_ChangeInFairValueOfCommonStockWarrantLiability" order="2" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/NoteDetail">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/NoteDetail0">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/NoteDetail00">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/NoteDetail000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/NoteDetail0000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShortTermInvestments" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShortTermInvestments"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShortTermInvestments" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/NoteDetail00000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_FairValueAssetsAndLiabilitiesTransferBetweenLevel1AndLevel2Level3TransferInOrOutDescription" xlink:href="clsn-20130331.xsd#clsn_FairValueAssetsAndLiabilitiesTransferBetweenLevel1AndLevel2Level3TransferInOrOutDescription"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_FairValueAssetsAndLiabilitiesTransferBetweenLevel1AndLevel2Level3TransferInOrOutDescription" order="1" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/NoteDetail000000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementEquityComponentsAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementEquityComponentsAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_EquityComponentDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_DebtInstrumentAxis" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentNameDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentNameDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_CapitalLeaseTransactionAxis" xlink:href="clsn-20130331.xsd#clsn_CapitalLeaseTransactionAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="clsn_CapitalLeaseTransactionAxis" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_CapitalLeaseTransactionDomain" xlink:href="clsn-20130331.xsd#clsn_CapitalLeaseTransactionDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="clsn_CapitalLeaseTransactionAxis" xlink:to="clsn_CapitalLeaseTransactionDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_CapitalLeaseTransactionDomain_0" xlink:href="clsn-20130331.xsd#clsn_CapitalLeaseTransactionDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="clsn_CapitalLeaseTransactionAxis" xlink:to="clsn_CapitalLeaseTransactionDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_WarrantMember" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_WarrantMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_WarrantMember" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_October2009CapitalLeaseMember" xlink:href="clsn-20130331.xsd#clsn_October2009CapitalLeaseMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CapitalLeaseTransactionDomain" xlink:to="clsn_October2009CapitalLeaseMember" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_November2011CapitalLeaseMember" xlink:href="clsn-20130331.xsd#clsn_November2011CapitalLeaseMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_CapitalLeaseTransactionDomain" xlink:to="clsn_November2011CapitalLeaseMember" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_TermALoanMember" xlink:href="clsn-20130331.xsd#clsn_TermALoanMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="clsn_TermALoanMember" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_CreditAgreementMember" xlink:href="clsn-20130331.xsd#clsn_CreditAgreementMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="clsn_CreditAgreementMember" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_LoanTrancheAmount" xlink:href="clsn-20130331.xsd#clsn_LoanTrancheAmount"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_LoanTrancheAmount" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_DebtInstrumentInterestRateStatedPercentage" order="3" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_NoteStockConversionRate" xlink:href="clsn-20130331.xsd#clsn_NoteStockConversionRate"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_NoteStockConversionRate" order="4" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockParOrStatedValuePerShare" order="5" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DebtConversionConvertedInstrumentWarrantsOrOptionsIssued1" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DebtConversionConvertedInstrumentWarrantsOrOptionsIssued1"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_DebtConversionConvertedInstrumentWarrantsOrOptionsIssued1" order="6" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_WarrantsIssuedExpirationPeriod" xlink:href="clsn-20130331.xsd#clsn_WarrantsIssuedExpirationPeriod"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_WarrantsIssuedExpirationPeriod" order="7" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredFinanceCostsNet" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_DeferredFinanceCostsNet" order="8" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueAssumptionsExpectedVolatilityRate" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueAssumptionsExpectedVolatilityRate"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_FairValueAssumptionsExpectedVolatilityRate" order="9" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueAssumptionsRiskFreeInterestRate" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueAssumptionsRiskFreeInterestRate"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_FairValueAssumptionsRiskFreeInterestRate" order="10" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueAssumptionsExpectedTerm" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueAssumptionsExpectedTerm"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_FairValueAssumptionsExpectedTerm" order="11" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueAssumptionsExercisePrice" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueAssumptionsExercisePrice"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_FairValueAssumptionsExercisePrice" order="12" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInPrepaidExpense" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_IncreaseDecreaseInPrepaidExpense"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_IncreaseDecreaseInPrepaidExpense" order="13" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LineOfCreditFacilityPeriodicPaymentInterest" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LineOfCreditFacilityPeriodicPaymentInterest"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_LineOfCreditFacilityPeriodicPaymentInterest" order="14" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CapitalLeasedAssetsGross" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CapitalLeasedAssetsGross"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CapitalLeasedAssetsGross" order="15" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DebtInstrumentPeriodicPayment" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DebtInstrumentPeriodicPayment"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_DebtInstrumentPeriodicPayment" order="16" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PaymentsForProceedsFromLoansAndLeases" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PaymentsForProceedsFromLoansAndLeases"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PaymentsForProceedsFromLoansAndLeases" order="17" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/NoteDetail0000000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementClassOfStockAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementClassOfStockAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ClassOfStockDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ClassOfStockDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_SeriesAConvertiblePreferredStockMember" xlink:href="clsn-20130331.xsd#clsn_SeriesAConvertiblePreferredStockMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="clsn_SeriesAConvertiblePreferredStockMember" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromIssuanceOrSaleOfEquity" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ProceedsFromIssuanceOrSaleOfEquity"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ProceedsFromIssuanceOrSaleOfEquity" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesNewIssues" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_AggregateOfferingPrice" xlink:href="clsn-20130331.xsd#clsn_AggregateOfferingPrice"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_AggregateOfferingPrice" order="3" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ProceedsFromIssuanceOfCommonStock" order="4" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_CommissiononProceedsfromATMSharesPercent" xlink:href="clsn-20130331.xsd#clsn_CommissiononProceedsfromATMSharesPercent"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_CommissiononProceedsfromATMSharesPercent" order="5" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_LegalFees" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_LegalFees"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_LegalFees" order="6" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ConvertiblePreferredStockSharesReservedForFutureIssuance" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ConvertiblePreferredStockSharesReservedForFutureIssuance"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ConvertiblePreferredStockSharesReservedForFutureIssuance" order="7" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" order="8" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights" order="9" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" order="10" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ConversionOfStockSharesConverted1" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ConversionOfStockSharesConverted1"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ConversionOfStockSharesConverted1" order="11" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_WarrantsAndRightsOutstanding" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_WarrantsAndRightsOutstanding"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_WarrantsAndRightsOutstanding" order="12" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DividendsPayableCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DividendsPayableCurrent"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_DividendsPayableCurrent" order="13" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/NoteDetail00000000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_StockOptionPlansMember" xlink:href="clsn-20130331.xsd#clsn_StockOptionPlansMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ScenarioUnspecifiedDomain" xlink:to="clsn_StockOptionPlansMember" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized" order="3" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensation" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensation"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensation" order="4" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" order="5" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" order="6" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" order="7" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" order="8" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromStockOptionsExercised" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ProceedsFromStockOptionsExercised"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ProceedsFromStockOptionsExercised" order="9" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" order="10" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" order="11" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" order="12" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/NoteDetail000000000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueByLiabilityClassAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_FairValueByLiabilityClassAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_FairValueByLiabilityClassAxis" xlink:to="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_FairValueByLiabilityClassAxis" xlink:to="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:to="us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis" xlink:to="us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_WarrantLiabilityMember" xlink:href="clsn-20130331.xsd#clsn_WarrantLiabilityMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:to="clsn_WarrantLiabilityMember" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_WarrantMember" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_WarrantMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_MajorTypesOfDebtAndEquitySecuritiesDomain" xlink:to="us-gaap_WarrantMember" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromWarrantExercises" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ProceedsFromWarrantExercises"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ProceedsFromWarrantExercises" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromIssuanceOfWarrants" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ProceedsFromIssuanceOfWarrants"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ProceedsFromIssuanceOfWarrants" order="3" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_ProceedsFromIssuanceOfWarrantsNet" xlink:href="clsn-20130331.xsd#clsn_ProceedsFromIssuanceOfWarrantsNet"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_ProceedsFromIssuanceOfWarrantsNet" order="4" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_CommonStockAndWarrantsIssuedShares" xlink:href="clsn-20130331.xsd#clsn_CommonStockAndWarrantsIssuedShares"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_CommonStockAndWarrantsIssuedShares" order="5" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_CommonStockSharesIssued" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_CommonStockSharesIssued"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockSharesIssued" order="6" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="invest_InvestmentWarrantsExercisePrice" xlink:href="http://xbrl.sec.gov/invest/2012/invest-2012-01-31.xsd#invest_InvestmentWarrantsExercisePrice"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="invest_InvestmentWarrantsExercisePrice" order="7" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms" order="8" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_CommonStockWarrantLiability" xlink:href="clsn-20130331.xsd#clsn_CommonStockWarrantLiability"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_CommonStockWarrantLiability" order="9" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_ChangeInFairValueOfCommonStockWarrantLiability" xlink:href="clsn-20130331.xsd#clsn_ChangeInFairValueOfCommonStockWarrantLiability"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_ChangeInFairValueOfCommonStockWarrantLiability" order="10" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/NoteDetail0000000000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementScenarioAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementScenarioAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_ScenarioUnspecifiedDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_AreaOfRealEstateProperty" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_AreaOfRealEstateProperty"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_AreaOfRealEstateProperty" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_LeaseTerm" xlink:href="clsn-20130331.xsd#clsn_LeaseTerm"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_LeaseTerm" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_NumberOfMonthsInWhichFreeRentIsProvided" xlink:href="clsn-20130331.xsd#clsn_NumberOfMonthsInWhichFreeRentIsProvided"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_NumberOfMonthsInWhichFreeRentIsProvided" order="3" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_PaymentsForRent" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_PaymentsForRent"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PaymentsForRent" order="4" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_LetterOfCreditRequiredByLeaseFaceAmount" xlink:href="clsn-20130331.xsd#clsn_LetterOfCreditRequiredByLeaseFaceAmount"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_LetterOfCreditRequiredByLeaseFaceAmount" order="5" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_ReductionAmountOnLetterOfCreditRequiredByLease" xlink:href="clsn-20130331.xsd#clsn_ReductionAmountOnLetterOfCreditRequiredByLease"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_ReductionAmountOnLetterOfCreditRequiredByLease" order="6" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_LetteOfCreditAmountRemainingUntilLeaseTermExpires" xlink:href="clsn-20130331.xsd#clsn_LetteOfCreditAmountRemainingUntilLeaseTermExpires"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_LetteOfCreditAmountRemainingUntilLeaseTermExpires" order="7" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/NoteDetail00000000000">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementTable" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementTable"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" order="0" xbrldt:contextElement="segment" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionBySupplierAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionBySupplierAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionBySupplierAxis" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionBySupplierAxis" xlink:to="us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionBySupplierAxis" xlink:to="us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_StatementClassOfStockAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementClassOfStockAxis" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ClassOfStockDomain" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ClassOfStockDomain_0" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_SupplyCommitmentAxis" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_SupplyCommitmentAxis"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_SupplyCommitmentAxis" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_SupplyCommitmentDomain" xlink:href="clsn-20130331.xsd#clsn_SupplyCommitmentDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_SupplyCommitmentAxis" xlink:to="clsn_SupplyCommitmentDomain" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_SupplyCommitmentDomain_0" xlink:href="clsn-20130331.xsd#clsn_SupplyCommitmentDomain"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_SupplyCommitmentAxis" xlink:to="clsn_SupplyCommitmentDomain_0" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_YakultAgreementMember" xlink:href="clsn-20130331.xsd#clsn_YakultAgreementMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="clsn_SupplyCommitmentDomain" xlink:to="clsn_YakultAgreementMember" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ConvertiblePreferredStockMember" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ConvertiblePreferredStockMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_ConvertiblePreferredStockMember" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_HisunMember" xlink:href="clsn-20130331.xsd#clsn_HisunMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain" xlink:to="clsn_HisunMember" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromLicenseFeesReceived" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ProceedsFromLicenseFeesReceived"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ProceedsFromLicenseFeesReceived" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_DeferredRevenue" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_DeferredRevenue"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_DeferredRevenue" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_DeferredRevenueAmortizationPeriod" xlink:href="clsn-20130331.xsd#clsn_DeferredRevenueAmortizationPeriod"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_DeferredRevenueAmortizationPeriod" order="3" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_OtherAccruedLiabilitiesCurrent" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_OtherAccruedLiabilitiesCurrent"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_OtherAccruedLiabilitiesCurrent" order="4" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="us-gaap_ProceedsFromIssuanceOfConvertiblePreferredStock" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_ProceedsFromIssuanceOfConvertiblePreferredStock"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ProceedsFromIssuanceOfConvertiblePreferredStock" order="5" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="clsn_ReductionInMilestonePayments" xlink:href="clsn-20130331.xsd#clsn_ReductionInMilestonePayments"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="clsn_ReductionInMilestonePayments" order="6" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:type="extended" xlink:role="http://www.celsion.com/role/DocumentAndEntityInformation">
    <loc xlink:type="locator" xlink:label="us-gaap_StatementLineItems" xlink:href="http://xbrl.fasb.org/us-gaap/2012/elts/us-gaap-2012-01-31.xsd#us-gaap_StatementLineItems"/>
    <loc xlink:type="locator" xlink:label="dei_EntityRegistrantName" xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_EntityRegistrantName"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="dei_EntityRegistrantName" order="0" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="dei_DocumentType" xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_DocumentType"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="dei_DocumentType" order="1" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="dei_CurrentFiscalYearEndDate" xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_CurrentFiscalYearEndDate"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="dei_CurrentFiscalYearEndDate" order="2" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="dei_EntityCommonStockSharesOutstanding" xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_EntityCommonStockSharesOutstanding"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="dei_EntityCommonStockSharesOutstanding" order="3" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="dei_EntityPublicFloat" xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_EntityPublicFloat"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="dei_EntityPublicFloat" order="4" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="dei_AmendmentFlag" xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_AmendmentFlag"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="dei_AmendmentFlag" order="5" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="dei_AmendmentDescription" xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_AmendmentDescription"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="dei_AmendmentDescription" order="6" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="dei_EntityCentralIndexKey" xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_EntityCentralIndexKey"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="dei_EntityCentralIndexKey" order="7" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="dei_EntityCurrentReportingStatus" xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_EntityCurrentReportingStatus"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="dei_EntityCurrentReportingStatus" order="8" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="dei_EntityVoluntaryFilers" xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_EntityVoluntaryFilers"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="dei_EntityVoluntaryFilers" order="9" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="dei_EntityFilerCategory" xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_EntityFilerCategory"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="dei_EntityFilerCategory" order="10" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="dei_EntityWellKnownSeasonedIssuer" xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_EntityWellKnownSeasonedIssuer"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="dei_EntityWellKnownSeasonedIssuer" order="11" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="dei_DocumentPeriodEndDate" xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_DocumentPeriodEndDate"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="dei_DocumentPeriodEndDate" order="12" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="dei_DocumentFiscalYearFocus" xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_DocumentFiscalYearFocus"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="dei_DocumentFiscalYearFocus" order="13" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="dei_DocumentFiscalPeriodFocus" xlink:href="http://xbrl.sec.gov/dei/2012/dei-2012-01-31.xsd#dei_DocumentFiscalPeriodFocus"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems" xlink:to="dei_DocumentFiscalPeriodFocus" order="14" xbrldt:closed="true"/>
  </definitionLink>
</linkbase>
