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  <headerData>
    <submissionType>13F-HR/A</submissionType>
    <filerInfo>
      <liveTestFlag>LIVE</liveTestFlag>
      <flags>
        <confirmingCopyFlag>false</confirmingCopyFlag>
        <returnCopyFlag>true</returnCopyFlag>
        <overrideInternetFlag>false</overrideInternetFlag>
      </flags>
      <filer>
        <credentials>
          <cik>0001423053</cik>
          <ccc>XXXXXXXX</ccc>
        </credentials>
      </filer>
      <periodOfReport>12-31-2018</periodOfReport>
    </filerInfo>
  </headerData>
  <formData>
    <coverPage>
      <reportCalendarOrQuarter>12-31-2018</reportCalendarOrQuarter>
      <isAmendment>true</isAmendment>
      <amendmentNo>2</amendmentNo>
      <amendmentInfo>
        <amendmentType>NEW HOLDINGS</amendmentType>
        <confDeniedExpired>true</confDeniedExpired>
        <dateDeniedExpired>08-14-2019</dateDeniedExpired>
        <dateReported>02-14-2019</dateReported>
        <reasonForNonConfidentiality>Confidential Treatment Expired</reasonForNonConfidentiality>
      </amendmentInfo>
      <filingManager>
        <name>CITADEL ADVISORS LLC</name>
        <address>
          <ns1:street1>131 S. DEARBORN ST., 32ND FLOOR</ns1:street1>
          <ns1:city>Chicago</ns1:city>
          <ns1:stateOrCountry>IL</ns1:stateOrCountry>
          <ns1:zipCode>60603</ns1:zipCode>
        </address>
      </filingManager>
      <reportType>13F HOLDINGS REPORT</reportType>
      <form13FFileNumber>028-13183</form13FFileNumber>
      <provideInfoForInstruction5>Y</provideInfoForInstruction5>
      <additionalInformation>THIS FILING LISTS SECURITIES HOLDINGS REPORTED ON THE FORM 13F FILED ON FEBRUARY 14, 2019, PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT THAT EXPIRED ON AUGUST 14, 2019.</additionalInformation>
    </coverPage>
    <signatureBlock>
      <name>Patricia A. Stasny</name>
      <title>Global Controller</title>
      <phone>312-395-4366</phone>
      <signature>Patricia A. Stasny</signature>
      <city>Chicago</city>
      <stateOrCountry>IL</stateOrCountry>
      <signatureDate>08-14-2019</signatureDate>
    </signatureBlock>
    <summaryPage>
      <otherIncludedManagersCount>0</otherIncludedManagersCount>
      <tableEntryTotal>1</tableEntryTotal>
      <tableValueTotal>17351</tableValueTotal>
      <isConfidentialOmitted>false</isConfidentialOmitted>
    </summaryPage>
  </formData>
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