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  <xs:element name="LiabiliessubjecttocompromiseTableTextBlock" id="siga_LiabiliessubjecttocompromiseTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xs:element name="ReorganizationitemsTableTextBlock" id="siga_ReorganizationitemsTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xs:element name="ReceivablesPercentage" id="siga_ReceivablesPercentage" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="instant" />
  <xs:element name="LabEquipmentMember" id="siga_LabEquipmentMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xs:element name="RecentAccountingPronouncementsAbstract" id="siga_RecentAccountingPronouncementsAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xs:element name="RevenuePercentage" id="siga_RevenuePercentage" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xs:element name="ReorganizationItemsPolicyPolicyTextBlock" id="siga_ReorganizationItemsPolicyPolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xs:element name="LiabilitiesSubjectToCompromisePolicyTextBlock" id="siga_LiabilitiesSubjectToCompromisePolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xs:element name="GoodwillPolicyPolicyTextBlock" id="siga_GoodwillPolicyPolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xs:element name="AccruedExpensesAndOtherCurrentLiabilitiesTextBlock" id="siga_AccruedExpensesAndOtherCurrentLiabilitiesTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xs:element name="AccruedExpensesAndOtherCurrentLiabilitiesTableTextBlock" id="siga_AccruedExpensesAndOtherCurrentLiabilitiesTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xs:element name="DocumentAndEntityInformationAbstract" id="siga_DocumentAndEntityInformationAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xs:element name="RestrictedStockUnits" id="siga_RestrictedStockUnits" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xs:element name="PharmAtheneliabilityincludesreimbursableattorneyandexpertfee" id="siga_PharmAtheneliabilityincludesreimbursableattorneyandexpertfee" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" />
  <xs:element name="PerDiemInterest" id="siga_PerDiemInterest" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" />
  <xs:element name="Reducedholdbackamount" id="siga_Reducedholdbackamount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" />
  <xs:element name="Invoicedmilestone" id="siga_Invoicedmilestone" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" />
  <xs:element name="Numberofcoursestobedeliveredtothegovernmentincludingfreecourses" id="siga_Numberofcoursestobedeliveredtothegovernmentincludingfreecourses" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="instant" />
  <xs:element name="NumberoffreecoursestobedeliveredtoBARDA" id="siga_NumberoffreecoursestobedeliveredtoBARDA" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="instant" />
  <xs:element name="HoldbackamountpendingFDAapproval" id="siga_HoldbackamountpendingFDAapproval" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" />
  <xs:element name="Numberofcoursesdeliveredtothegovernment" id="siga_Numberofcoursesdeliveredtothegovernment" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xs:element name="IncreaseinpaymentsfordeliveryofcoursesofTPOXX" id="siga_IncreaseinpaymentsfordeliveryofcoursesofTPOXX" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" />
  <xs:element name="FutureproceedstobereceivedfromBARDA" id="siga_FutureproceedstobereceivedfromBARDA" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" />
  <xs:element name="Futureproceedstobereceivedfromthefuturedeliveriesofcoursestothegovernment" id="siga_Futureproceedstobereceivedfromthefuturedeliveriesofcoursestothegovernment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" />
  <xs:element name="AmountofoptiontobereceivedfromBARDAforapprovalforextensionof84mothexpiry" id="siga_AmountofoptiontobereceivedfromBARDAforapprovalforextensionof84mothexpiry" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" />
  <xs:element name="NumberofcoursesofTPOXXtobedeliveredtothegovernment" id="siga_NumberofcoursesofTPOXXtobedeliveredtothegovernment" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="instant" />
  <xs:element name="CovenantsonpharmAtheneliability" id="siga_CovenantsonpharmAtheneliability" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="instant" />
  <xs:element name="Paymenttoextend120daystosatisfypharmAtheneclaim" id="siga_Paymenttoextend120daystosatisfypharmAtheneclaim" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" />
  <xs:element name="PharmAtheneliabilityinterest" id="siga_PharmAtheneliabilityinterest" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" />
  <xs:element name="IncreasedecreaseinPharmAtheneliability" id="siga_IncreasedecreaseinPharmAtheneliability" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
</xs:schema>