<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>
    <periodOfReport>2003-11-28</periodOfReport>
    <notSubjectToSection16>1</notSubjectToSection16>
    <issuer>
        <issuerCik>0000101778</issuerCik>
        <issuerName>MARATHON OIL CORP</issuerName>
        <issuerTradingSymbol>MRO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001238374</rptOwnerCik>
            <rptOwnerName>MILLS JOHN T</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O MARATHON OIL CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>5555 SAN FELIPE ROAD</rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77056</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CHIEF FINANCIAL OFFICER</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>
  <nonDerivativeTable>
   <nonDerivativeTransaction>
      <securityTitle>
          <value>COMMON STOCK</value>
      </securityTitle>
      <transactionDate>
          <value>2003-11-28</value>
      </transactionDate>
      <transactionCoding>
          <transactionFormType>4</transactionFormType>
          <transactionCode>D</transactionCode>
          <equitySwapInvolved>0</equitySwapInvolved>
      </transactionCoding>
      <transactionTimeliness>
      <value />
      </transactionTimeliness>
      <transactionAmounts>
          <transactionShares>
              <value>23600.00</value>
              <footnoteId id="F1" />
          </transactionShares>
          <transactionPricePerShare>
              <value>0</value>
          </transactionPricePerShare>
          <transactionAcquiredDisposedCode>
              <value>D</value>
          </transactionAcquiredDisposedCode>
      </transactionAmounts>
      <postTransactionAmounts>
          <sharesOwnedFollowingTransaction>
              <value>59730.00</value>
              <footnoteId id="F2" />
          </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
          <directOrIndirectOwnership>
              <value>D</value>
          </directOrIndirectOwnership>
      </ownershipNature>
   </nonDerivativeTransaction>
  </nonDerivativeTable>
  <derivativeTable>
   <derivativeTransaction>
      <securityTitle>
          <value>Phantom Stock</value>
      </securityTitle>
      <conversionOrExercisePrice>
              <footnoteId id="F3" />
      </conversionOrExercisePrice>
      <transactionDate>
          <value>2003-11-28</value>
      </transactionDate>
      <transactionCoding>
          <transactionFormType>4</transactionFormType>
          <transactionCode>I</transactionCode>
          <equitySwapInvolved>0</equitySwapInvolved>
      </transactionCoding>
      <transactionAmounts>
          <transactionShares>
              <value>517.65</value>
          </transactionShares>
          <transactionPricePerShare>
              <value>29.61</value>
          </transactionPricePerShare>
          <transactionAcquiredDisposedCode>
              <value>D</value>
          </transactionAcquiredDisposedCode>
      </transactionAmounts>
      <exerciseDate>
              <footnoteId id="F4" />
      </exerciseDate>
      <expirationDate>
              <footnoteId id="F5" />
      </expirationDate>
      <underlyingSecurity>
          <underlyingSecurityTitle>
              <value>COMMON STOCK</value>
          </underlyingSecurityTitle>
          <underlyingSecurityShares>
              <value>517.65</value>
          </underlyingSecurityShares>
      </underlyingSecurity>
      <postTransactionAmounts>
          <sharesOwnedFollowingTransaction>
              <value>0.00</value>
          </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
          <directOrIndirectOwnership>
              <value>D</value>
          </directOrIndirectOwnership>
      </ownershipNature>
   </derivativeTransaction>
  </derivativeTable>
<footnotes>
   <footnote id="F1">Forfeiture for no value of 7,800 shares of restricted stock granted under Marathon Oil Corporation's 1990 Stock Plan and 15,800 p
erformance shares granted under Marathon Oil Corporation's 2003 Incentive Compensation Plan.</footnote>
   <footnote id="F2">Includes 151.691 shares, previously not reported, for dividends allocated to issuer stock fund for reporting person's account in
Marathon Oil Company Thrift Plan.</footnote>
   <footnote id="F3">1 for 1.</footnote>
   <footnote id="F4">Immediately</footnote>
   <footnote id="F5">Shares of Phantom Stock are payable in cash following the termination of the reporting person's employment under the United State
s Steel Corporation Supplemental Thrift Program.</footnote>
</footnotes>
<remarks></remarks>    <ownerSignature>
       <signatureName>By: R. J. Kolencik, Attorney-in-Fact for John T. Mills</signatureName>
       <signatureDate>2003-12-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0201
4
2003-11-28
1
0000101778
MARATHON OIL CORP
MRO
0001238374
MILLS JOHN T
C/O MARATHON OIL CORPORATION
5555 SAN FELIPE ROAD
HOUSTON
TX
77056
0
1
0
0
CHIEF FINANCIAL OFFICER
COMMON STOCK
2003-11-28
4
D
0
23600.00
0
D
59730.00
D
Phantom Stock
2003-11-28
4
I
0
517.65
29.61
D
COMMON STOCK
517.65
0.00
D
Forfeiture for no value of 7,800 shares of restricted stock granted under Marathon Oil Corporation's 1990 Stock Plan and 15,800 p
erformance shares granted under Marathon Oil Corporation's 2003 Incentive Compensation Plan.
Includes 151.691 shares, previously not reported, for dividends allocated to issuer stock fund for reporting person's account in
Marathon Oil Company Thrift Plan.
1 for 1.
Immediately
Shares of Phantom Stock are payable in cash following the termination of the reporting person's employment under the United State
s Steel Corporation Supplemental Thrift Program.
By: R. J. Kolencik, Attorney-in-Fact for John T. Mills
2003-12-02