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  <xs:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfSharesThatCouldBeIssued" id="siga_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfSharesThatCouldBeIssued" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xs:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndExpectedToVestWeightedAverageRemainingLife" id="siga_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndExpectedToVestWeightedAverageRemainingLife" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xs:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExcercisedWeightedAverageExcercisePrice" id="siga_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExcercisedWeightedAverageExcercisePrice" type="num:perShareItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xs:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsCanceledExpiredWeightedAverageExcercisePrice" id="siga_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsCanceledExpiredWeightedAverageExcercisePrice" type="num:perShareItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xs:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantedWeightedAverageExcercisePrice" id="siga_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantedWeightedAverageExcercisePrice" type="num:perShareItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xs:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingWeightedAverageExercisePrice" id="siga_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingWeightedAverageExercisePrice" type="num:perShareItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="instant" />
  <xs:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableIntrinsicValue" id="siga_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableIntrinsicValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" />
  <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="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="RecentAccountingPronouncementsAbstract" id="siga_RecentAccountingPronouncementsAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xs:element name="AdministrationOfChapter11CaseTextBlock" id="siga_AdministrationOfChapter11CaseTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <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="RestrictedStockUnits" id="siga_RestrictedStockUnits" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" abstract="false" xbrli:periodType="duration" />
  <xs:element name="FairValueMeasurementsAbstract" id="siga_FairValueMeasurementsAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
  <xs:element name="AdministrationofChapter11CaseAbstract" id="siga_AdministrationofChapter11CaseAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" abstract="true" xbrli:periodType="duration" />
</xs:schema>