﻿<?xml version="1.0" encoding="utf-8"?>
<Return xmlns="http://www.irs.gov/efile" xsi:schemaLocation="http://www.irs.gov/efile" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" returnVersion="2017v2.3">
  <ReturnHeader binaryAttachmentCnt="0">
    <ReturnTs>2019-05-14T11:26:42-05:00</ReturnTs>
    <TaxPeriodEndDt>2018-06-30</TaxPeriodEndDt>
    <PreparerFirmGrp>
      <PreparerFirmName>
        <BusinessNameLine1Txt>Grant Thornton LLP</BusinessNameLine1Txt>
      </PreparerFirmName>
      <PreparerUSAddress>
        <AddressLine1Txt>1000 WILSON BLVD SUITE 1400</AddressLine1Txt>
        <CityNm>ARLINGTON</CityNm>
        <StateAbbreviationCd>VA</StateAbbreviationCd>
        <ZIPCd>22209</ZIPCd>
      </PreparerUSAddress>
    </PreparerFirmGrp>
    <ReturnTypeCd>990EZ</ReturnTypeCd>
    <TaxPeriodBeginDt>2017-07-01</TaxPeriodBeginDt>
    <Filer>
      <EIN>521640399</EIN>
      <BusinessName>
        <BusinessNameLine1Txt>CHILDREN'S HOSPITAL SELF-INSURANCE TRUST</BusinessNameLine1Txt>
      </BusinessName>
      <InCareOfNm>% CORPORATE OFFICERS</InCareOfNm>
      <BusinessNameControlTxt>CHIL</BusinessNameControlTxt>
      <PhoneNum>2024765000</PhoneNum>
      <USAddress>
        <AddressLine1Txt>111 MICHIGAN AVENUE NW</AddressLine1Txt>
        <CityNm>WASHINGTON</CityNm>
        <StateAbbreviationCd>DC</StateAbbreviationCd>
        <ZIPCd>20010</ZIPCd>
      </USAddress>
    </Filer>
    <BusinessOfficerGrp>
      <PersonNm>ALEC KING</PersonNm>
      <PersonTitleTxt>CFO</PersonTitleTxt>
      <PhoneNum>2024765000</PhoneNum>
      <SignatureDt>2019-05-03</SignatureDt>
      <DiscussWithPaidPreparerInd>true</DiscussWithPaidPreparerInd>
    </BusinessOfficerGrp>
    <PreparerPersonGrp>
      <PreparerPersonNm>Mary Torretta</PreparerPersonNm>
      <PTIN>P00847851</PTIN>
      <PhoneNum>7038477500</PhoneNum>
      <PreparationDt>2019-04-26</PreparationDt>
    </PreparerPersonGrp>
    <FilingSecurityInformation>
      <IPAddress>
        <IPv4AddressTxt>209.220.136.124</IPv4AddressTxt>
      </IPAddress>
      <FederalOriginalSubmissionId>54681420191345000001</FederalOriginalSubmissionId>
      <FederalOriginalSubmissionIdDt>2019-05-14</FederalOriginalSubmissionIdDt>
      <FilingLicenseTypeCd>P</FilingLicenseTypeCd>
      <AtSubmissionCreationDeviceId>AA918D8483008E32154F6CC583B06457B9AF9E42</AtSubmissionCreationDeviceId>
      <AtSubmissionFilingDeviceId>F3025B962F5CDC81089D134DBE2E83273904A17C</AtSubmissionFilingDeviceId>
    </FilingSecurityInformation>
    <TaxYr>2017</TaxYr>
    <BuildTS>2019-02-21 02:37:17Z</BuildTS>
  </ReturnHeader>
  <ReturnData documentCnt="3">
    <IRS990EZ documentId="IRS990EZ" referenceDocumentId="IRS990ScheduleO">
      <MethodOfAccountingAccrualInd>X</MethodOfAccountingAccrualInd>
      <ScheduleBNotRequiredInd>X</ScheduleBNotRequiredInd>
      <WebsiteAddressTxt>N/A</WebsiteAddressTxt>
      <Organization501c3Ind referenceDocumentId="IRS990ScheduleA">X</Organization501c3Ind>
      <TypeOfOrganizationTrustInd>X</TypeOfOrganizationTrustInd>
      <GrossReceiptsAmt>0</GrossReceiptsAmt>
      <InfoInScheduleOPartIInd>X</InfoInScheduleOPartIInd>
      <CostOrOtherBasisExpenseSaleAmt>0</CostOrOtherBasisExpenseSaleAmt>
      <GainOrLossFromSaleOfAssetsAmt>0</GainOrLossFromSaleOfAssetsAmt>
      <SpecialEventsDirectExpensesAmt>0</SpecialEventsDirectExpensesAmt>
      <SpecialEventsNetIncomeLossAmt>0</SpecialEventsNetIncomeLossAmt>
      <CostOfGoodsSoldAmt>0</CostOfGoodsSoldAmt>
      <GrossProfitLossSlsOfInvntryAmt>0</GrossProfitLossSlsOfInvntryAmt>
      <TotalRevenueAmt>0</TotalRevenueAmt>
      <SalariesOtherCompEmplBnftAmt>41453</SalariesOtherCompEmplBnftAmt>
      <FeesAndOtherPymtToIndCntrctAmt>2507129</FeesAndOtherPymtToIndCntrctAmt>
      <OtherExpensesTotalAmt>10206369</OtherExpensesTotalAmt>
      <TotalExpensesAmt>12754951</TotalExpensesAmt>
      <ExcessOrDeficitForYearAmt>-12754951</ExcessOrDeficitForYearAmt>
      <NetAssetsOrFundBalancesBOYAmt>0</NetAssetsOrFundBalancesBOYAmt>
      <OtherChangesInNetAssetsAmt>12754951</OtherChangesInNetAssetsAmt>
      <InfoInScheduleOPartIIInd>X</InfoInScheduleOPartIIInd>
      <CashSavingsAndInvestmentsGrp>
        <BOYAmt>118519</BOYAmt>
        <EOYAmt>397424</EOYAmt>
      </CashSavingsAndInvestmentsGrp>
      <LandAndBuildingsGrp>
        <BOYAmt>0</BOYAmt>
        <EOYAmt>0</EOYAmt>
      </LandAndBuildingsGrp>
      <OtherAssetsTotalDetail>
        <BOYAmt>0</BOYAmt>
        <EOYAmt>0</EOYAmt>
      </OtherAssetsTotalDetail>
      <Form990TotalAssetsGrp>
        <BOYAmt>118519</BOYAmt>
        <EOYAmt>397424</EOYAmt>
      </Form990TotalAssetsGrp>
      <SumOfTotalLiabilitiesGrp>
        <BOYAmt>118519</BOYAmt>
        <EOYAmt>397424</EOYAmt>
      </SumOfTotalLiabilitiesGrp>
      <NetAssetsOrFundBalancesGrp>
        <BOYAmt>0</BOYAmt>
        <EOYAmt>0</EOYAmt>
      </NetAssetsOrFundBalancesGrp>
      <InfoInScheduleOPartIIIInd>X</InfoInScheduleOPartIIIInd>
      <PrimaryExemptPurposeTxt>MALPRACTICE/GENERAL LIABILITY INSURANCE</PrimaryExemptPurposeTxt>
      <ProgramSrvcAccomplishmentGrp>
        <DescriptionProgramSrvcAccomTxt>CHILDREN'S HOSPITAL SELF-INSURANCE TRUST WAS CREATED TO PROVIDE A MECHANISM FOR PAYING MALPRACTICE AND COMPREHENSIVE GENERAL LIABILITY CLAIMS ARISING AGAINST CHILDREN'S HOSPITAL AND OTHER AFFILIATED ENTITIES AS WELL AS INDIVIDUALS PERFORMING SERVICES FOR OR ON BEHALF OF THE AFFILIATED ORGANIZATIONS.</DescriptionProgramSrvcAccomTxt>
        <GrantsAndAllocationsAmt>0</GrantsAndAllocationsAmt>
        <ProgramServiceExpensesAmt>10206369</ProgramServiceExpensesAmt>
      </ProgramSrvcAccomplishmentGrp>
      <TotalProgramServiceExpensesAmt>10206369</TotalProgramServiceExpensesAmt>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>SEDGWICK CLAIMS MANAGEMENT SERVICES</PersonNm>
        <TitleTxt>INSTITUTIONAL TRUSTEE</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>1.0</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>41453</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <ActivitiesNotPreviouslyRptInd>false</ActivitiesNotPreviouslyRptInd>
      <ChgMadeToOrgnzngDocNotRptInd>false</ChgMadeToOrgnzngDocNotRptInd>
      <OrganizationHadUBIInd>false</OrganizationHadUBIInd>
      <SubjectToProxyTaxInd>false</SubjectToProxyTaxInd>
      <OrganizationDissolvedEtcInd>false</OrganizationDissolvedEtcInd>
      <Form1120PolFiledInd>false</Form1120PolFiledInd>
      <MadeLoansToFromOfficersInd>false</MadeLoansToFromOfficersInd>
      <TaxImposedUnderIRC4911Amt>0</TaxImposedUnderIRC4911Amt>
      <TaxImposedUnderIRC4912Amt>0</TaxImposedUnderIRC4912Amt>
      <TaxImposedUnderIRC4955Amt>0</TaxImposedUnderIRC4955Amt>
      <EngagedInExcessBenefitTransInd>false</EngagedInExcessBenefitTransInd>
      <TaxImposedOnOrganizationMgrAmt>0</TaxImposedOnOrganizationMgrAmt>
      <TaxReimbursedByOrganizationAmt>0</TaxReimbursedByOrganizationAmt>
      <ProhibitedTaxShelterTransInd>false</ProhibitedTaxShelterTransInd>
      <StatesWhereCopyOfReturnIsFldCd>DC</StatesWhereCopyOfReturnIsFldCd>
      <BooksInCareOfDetail>
        <PersonNm>CORPORATE OFFICERS</PersonNm>
        <USAddress>
          <AddressLine1Txt>111 MICHIGAN AVENUE NW</AddressLine1Txt>
          <CityNm>WASHINGTON</CityNm>
          <StateAbbreviationCd>DC</StateAbbreviationCd>
          <ZIPCd>20010</ZIPCd>
        </USAddress>
        <PhoneNum>3015726283</PhoneNum>
      </BooksInCareOfDetail>
      <ForeignFinancialAccountInd>false</ForeignFinancialAccountInd>
      <ForeignOfficeInd>false</ForeignOfficeInd>
      <DonorAdvisedFndsInd>false</DonorAdvisedFndsInd>
      <OperateHospitalInd>false</OperateHospitalInd>
      <TanningServicesProvidedInd>false</TanningServicesProvidedInd>
      <RelatedOrganizationCtrlEntInd>false</RelatedOrganizationCtrlEntInd>
      <TransactionWithControlEntInd>false</TransactionWithControlEntInd>
      <PoliticalCampaignActyInd>false</PoliticalCampaignActyInd>
      <InfoInScheduleOPartVIInd>X</InfoInScheduleOPartVIInd>
      <LobbyingActivitiesInd>false</LobbyingActivitiesInd>
      <SchoolOperatingInd>false</SchoolOperatingInd>
      <TrnsfrExmptNonChrtblRltdOrgInd>false</TrnsfrExmptNonChrtblRltdOrgInd>
      <PartVIOfCompOfHghstPdEmplTxt>NONE</PartVIOfCompOfHghstPdEmplTxt>
      <OtherEmployeePaidOver100kCnt>0</OtherEmployeePaidOver100kCnt>
      <CompensationOfHghstPdCntrctGrp>
        <PersonNm>ARMSTRONG DONOHUE CEPPOS</PersonNm>
        <USAddress>
          <AddressLine1Txt>204 MONROE STREET SUITE 101</AddressLine1Txt>
          <CityNm>ROCKVILLE</CityNm>
          <StateAbbreviationCd>MD</StateAbbreviationCd>
          <ZIPCd>20850</ZIPCd>
        </USAddress>
        <ServiceTypeTxt>LEGAL SERVICES</ServiceTypeTxt>
        <CompensationAmt>432295</CompensationAmt>
      </CompensationOfHghstPdCntrctGrp>
      <CompensationOfHghstPdCntrctGrp>
        <PersonNm>JACKSON AND CAMPBELL PC</PersonNm>
        <USAddress>
          <AddressLine1Txt>1120 20TH STREET NW Suite 300</AddressLine1Txt>
          <CityNm>WASHINGTON</CityNm>
          <StateAbbreviationCd>DC</StateAbbreviationCd>
          <ZIPCd>20036</ZIPCd>
        </USAddress>
        <ServiceTypeTxt>LEGAL SERVICES</ServiceTypeTxt>
        <CompensationAmt>425652</CompensationAmt>
      </CompensationOfHghstPdCntrctGrp>
      <CompensationOfHghstPdCntrctGrp>
        <PersonNm>MILES AND STOCKBRIDGE</PersonNm>
        <USAddress>
          <AddressLine1Txt>1500 K STREET NW</AddressLine1Txt>
          <CityNm>WASHINGTON</CityNm>
          <StateAbbreviationCd>DC</StateAbbreviationCd>
          <ZIPCd>200051209</ZIPCd>
        </USAddress>
        <ServiceTypeTxt>LEGAL SERVICES</ServiceTypeTxt>
        <CompensationAmt>419071</CompensationAmt>
      </CompensationOfHghstPdCntrctGrp>
      <CompensationOfHghstPdCntrctGrp>
        <PersonNm>WILSON ELSER MOSKOWITZ EDELMAN DICK</PersonNm>
        <USAddress>
          <AddressLine1Txt>700 11TH STREET NW SUITE 400</AddressLine1Txt>
          <CityNm>WASHINGTON</CityNm>
          <StateAbbreviationCd>DC</StateAbbreviationCd>
          <ZIPCd>20001</ZIPCd>
        </USAddress>
        <ServiceTypeTxt>LEGAL SERVICES</ServiceTypeTxt>
        <CompensationAmt>149255</CompensationAmt>
      </CompensationOfHghstPdCntrctGrp>
      <CompensationOfHghstPdCntrctGrp>
        <PersonNm>SEYFARTH SHAW LLP</PersonNm>
        <USAddress>
          <AddressLine1Txt>815 CONNECTICUT AVENUE NW</AddressLine1Txt>
          <CityNm>WASHINGTON</CityNm>
          <StateAbbreviationCd>DC</StateAbbreviationCd>
          <ZIPCd>20006</ZIPCd>
        </USAddress>
        <ServiceTypeTxt>LEGAL SERVICES</ServiceTypeTxt>
        <CompensationAmt>134813</CompensationAmt>
      </CompensationOfHghstPdCntrctGrp>
      <CntrctRcvdGreaterThan100KCnt>2</CntrctRcvdGreaterThan100KCnt>
      <FiledScheduleAInd>true</FiledScheduleAInd>
    </IRS990EZ>
    <IRS990ScheduleA documentId="IRS990ScheduleA">
      <SupportingOrganization509a3Ind>X</SupportingOrganization509a3Ind>
      <SupportingOrgType3FuncIntInd>X</SupportingOrgType3FuncIntInd>
      <SupportedOrganizationsCnt>1</SupportedOrganizationsCnt>
      <SupportedOrgInformationGrp>
        <SupportedOrganizationName>
          <BusinessNameLine1Txt>CHILDREN'S HOSPITAL</BusinessNameLine1Txt>
        </SupportedOrganizationName>
        <EIN>530196580</EIN>
        <OrganizationTypeCd>3</OrganizationTypeCd>
        <GoverningDocumentListedInd>true</GoverningDocumentListedInd>
        <SupportAmt>12754951</SupportAmt>
        <OtherSupportAmt>0</OtherSupportAmt>
      </SupportedOrgInformationGrp>
      <SupportedOrganizationsTotalCnt>1</SupportedOrganizationsTotalCnt>
      <SupportSumAmt>12754951</SupportSumAmt>
      <OtherSupportSumAmt>0</OtherSupportSumAmt>
      <Form990SchASupportingOrgGrp>
        <ListedByNameGoverningDocInd>true</ListedByNameGoverningDocInd>
        <SuprtOrgNoIRSDeterminationInd>false</SuprtOrgNoIRSDeterminationInd>
        <SupportedOrgSectionC456Ind>false</SupportedOrgSectionC456Ind>
        <SupportedOrgNotOrganizedUSInd>false</SupportedOrgNotOrganizedUSInd>
        <OrganizationChangeSuprtOrgInd>false</OrganizationChangeSuprtOrgInd>
        <SupportNonSupportedOrgInd>false</SupportNonSupportedOrgInd>
        <PaymentSubstantialContribtrInd>false</PaymentSubstantialContribtrInd>
        <LoanDisqualifiedPersonInd>false</LoanDisqualifiedPersonInd>
        <ControlledDisqualifiedPrsnInd>false</ControlledDisqualifiedPrsnInd>
        <DisqualifiedPrsnControllIntInd>false</DisqualifiedPrsnControllIntInd>
        <DisqualifiedPrsnOwnrIntInd>false</DisqualifiedPrsnOwnrIntInd>
        <ExcessBusinessHoldingsRulesInd>false</ExcessBusinessHoldingsRulesInd>
        <ContributionControllerInd>false</ContributionControllerInd>
        <ContributionFamilyInd>false</ContributionFamilyInd>
        <Contribution35ControlledInd>false</Contribution35ControlledInd>
      </Form990SchASupportingOrgGrp>
      <Form990SchAType3SprtOrgAllGrp>
        <TimelyProvidedDocumentsInd>true</TimelyProvidedDocumentsInd>
        <OfficersCloseRelationshipInd>false</OfficersCloseRelationshipInd>
        <SupportedOrgVoiceInvestmentInd>true</SupportedOrgVoiceInvestmentInd>
      </Form990SchAType3SprtOrgAllGrp>
      <Form990SchAType3FuncIntGrp>
        <ActivitiesTestInd>X</ActivitiesTestInd>
        <ActivitiesFurtherExemptPrpsInd>true</ActivitiesFurtherExemptPrpsInd>
        <ActivitiesEngagedOrgInvlmntInd>true</ActivitiesEngagedOrgInvlmntInd>
      </Form990SchAType3FuncIntGrp>
      <Form990ScheduleAPartVIGrp>
        <FormAndLineReferenceDesc>FORM 990-EZ, SCHEDULE A, PART IV, SECTION D, LINES 2 AND 3</FormAndLineReferenceDesc>
        <ExplanationTxt>THE SUPPORTED ORGANIZATION, CHILDREN'S HOSPITAL (THE HOSPITAL), RETAINS OWNERSHIP OF ALL INCOME AND ASSETS OF CHILDREN'S HOSPITAL SELF-INSURANCE TRUST FUND (SELF-INSURANCE TRUST). THE HOSPITAL'S BOARD OF DIRECTORS AND/OR ADMINISTRATIVE OFFICERS PROVIDE OVERSIGHT AND FINAL CONSENT AUTHORITY OVER THE SELF-INSURANCE TRUST. ADDITIONALLY, ALL CLAIMS AND CLAIM SETTLEMENTS ARE SUPERVISED AND AUTHORIZED BY THE HOSPITAL'S PROVIDERS' REPRESENTATIVES IN ADDITION TO BOARD ADMINISTRATORS AND PROFESSIONAL CONSULTANT PERSONNEL.</ExplanationTxt>
      </Form990ScheduleAPartVIGrp>
      <Form990ScheduleAPartVIGrp>
        <FormAndLineReferenceDesc>FORM 990-EZ, SCHEDULE A, PART IV, SECTION E, LINE 2A</FormAndLineReferenceDesc>
        <ExplanationTxt>IN OCTOBER 1976, THE HOSPITAL ESTABLISHED THE FILING ORGANIZATION, A SELF-INSURANCE TRUST, TO PROVIDE A SELF-INSURANCE MECHANISM TO PAY PROFESSIONAL AND COMPREHENSIVE GENERAL LIABILITY CLAIMS OR SUITS AGAINST THE HOSPITAL AND ITS EMPLOYEES. OVER THE YEARS, THE CORPUS OF THE SELF-INSURANCE TRUST HAS INCREASED AS WELL AS THE NUMBER AND CATEGORIES OVER COVERED PERSONS. THE CATEGORIES AND SCOPE OF COVERAGE UNDER THE TRUST HAVE ALSO INCREASED IN ORDER TO ALLOW THE HOSPITAL TO FURTHER ITS EXEMPT ACTIVITIES.</ExplanationTxt>
      </Form990ScheduleAPartVIGrp>
      <Form990ScheduleAPartVIGrp>
        <FormAndLineReferenceDesc>FORM 990-EZ, SCHEDULE A, PART IV, SECTION E, LINE 2B</FormAndLineReferenceDesc>
        <ExplanationTxt>THE SELF-INSURANCE TRUST WAS CREATED TO PROVIDE A MECHANISM TO PAY MALPRACTICE AND COMPREHENSIVE GENERAL LIABILITY CLAIMS ARISING AGAINST CHILDREN'S HOSPITAL (EIN:53-0196580) IN FURTHERANCE OF ITS CHARITABLE PURPOSE OF PROVIDING MEDICAL CARE TO CHILDREN AND OTHER AFFILIATED ENTITIES AS WELL AS INDIVIDUALS PERFORMING SERVICES FOR OR ON BEHALF OF THE AFFILIATED ORGINIZATIONS. THE HOSPITAL OR OTHER AFFILIATED ENTITIES WOULD BE REQUIRED TO PERFORM THESE DUTIES IF NOT FOR THE ESTABLISHMENT OF THE SELF-INSURANCE TRUST.</ExplanationTxt>
      </Form990ScheduleAPartVIGrp>
    </IRS990ScheduleA>
    <IRS990ScheduleO documentId="IRS990ScheduleO">
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990EZ PART I LINE 16</FormAndLineReferenceDesc>
        <ExplanationTxt>Description:CLAIM SETTLEMENTS Amount:10206369</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990EZ PART I LINE 20</FormAndLineReferenceDesc>
        <ExplanationTxt>Description:TRANSFERS FROM AFFILIATE Amount:12754951</ExplanationTxt>
      </SupplementalInformationDetail>
    </IRS990ScheduleO>
  </ReturnData>
</Return>