<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

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    <periodOfReport>2006-08-11</periodOfReport>

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    <issuer>
        <issuerCik>0000101778</issuerCik>
        <issuerName>MARATHON OIL CORP</issuerName>
        <issuerTradingSymbol>MRO</issuerTradingSymbol>
    </issuer>

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            <rptOwnerCik>0001331928</rptOwnerCik>
            <rptOwnerName>Heminger Gary R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
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            <rptOwnerStreet2>5555 SANFELIPE ROAD5555 SANFELIPE 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>Executive Vice President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

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            <transactionTimeliness>
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                </transactionShares>
                <transactionPricePerShare>
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                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
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                </transactionAcquiredDisposedCode>
            </transactionAmounts>
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                </transactionShares>
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                </transactionPricePerShare>
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                </transactionAcquiredDisposedCode>
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                </transactionPricePerShare>
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            </transactionAmounts>
            <exerciseDate>
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            </exerciseDate>
            <expirationDate>
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            <postTransactionAmounts>
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                </sharesOwnedFollowingTransaction>
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                </directOrIndirectOwnership>
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        </derivativeTransaction>
    </derivativeTable>

    <ownerSignature>
        <signatureName>W. F. Schwind, Jr., Attorney-in-Fact for Gary R. Heminger</signatureName>
        <signatureDate>2006-08-14</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0202
4
2006-08-11
0
0000101778
MARATHON OIL CORP
MRO
0001331928
Heminger Gary R
C/O MARATHON OIL CORPORATIONC/O MARATHON
5555 SANFELIPE ROAD5555 SANFELIPE ROAD
HOUSTON
TX
77056
0
1
0
0
Executive Vice President
COMMON STOCK
2006-08-11
4
M
0
2700.0000
29.375
A
59654.6950
D
COMMON STOCK
2006-08-11
4
M
0
4000.0000
29.375
A
63654.6950
D
COMMON STOCK
2006-08-11
4
S
0
3600.0000
90.00
D
60054.6950
D
EMPLOYEE STOCK OPTION (Right to Buy)
29.375
2006-08-11
4
M
0
2700.00
0
D
1998-05-27
2007-05-27
COMMON STOCK
2700.00
0.00
D
EMPLOYEE STOCK OPTION (Right to Buy)
29.375
2006-08-11
4
M
0
4000.00
0
D
2000-05-25
2009-05-25
COMMON STOCK
4000.00
7000.00
D
W. F. Schwind, Jr., Attorney-in-Fact for Gary R. Heminger
2006-08-14