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<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-12-28</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001022321</issuerCik>
        <issuerName>GENESIS ENERGY LP</issuerName>
        <issuerTradingSymbol>GEL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001403411</rptOwnerCik>
            <rptOwnerName>Davison James E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2000 FARMERVILLE HIGHWAY</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>RUSTON</rptOwnerCity>
            <rptOwnerState>LA</rptOwnerState>
            <rptOwnerZipCode>71270</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

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                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1049406</value>
                </transactionShares>
                <transactionPricePerShare>
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                    <value>2877610</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
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                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
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        <derivativeTransaction>
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            <securityTitle>
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                <value></value>
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                </sharesOwnedFollowingTransaction>
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                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Waiver Units - Class 4</value>
            </securityTitle>
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            </conversionOrExercisePrice>
            <transactionDate>
                <value>2010-12-28</value>
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            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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                <value></value>
            </transactionTimeliness>
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                    <value>91823</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F1"/>
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                    <value>A</value>
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                <value>2021-01-01</value>
                <footnoteId id="F3"/>
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                <underlyingSecurityTitle>
                    <value>Common Units - Class A</value>
                </underlyingSecurityTitle>
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                    <value>91823</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
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                    <value>91823</value>
                </sharesOwnedFollowingTransaction>
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    <footnotes>
        <footnote id="F1">Pursuant to the Agreement and Plan of Merger, dated as of December 28, 2010, by and among Genesis Energy, L.P. (the &quot;Partnership&quot;), Genesis Acquisition, LLC and Genesis Energy, LLC (the &quot;Merger Agreement&quot;) as Merger Consideration (as defined in the Merger Agreement).  On the effective date of the merger, the closing price of the Common Units - Class A of the Partnership on the New York Stock Exchange was $26.24.</footnote>
        <footnote id="F2">The Waiver Units, among other rights, preferences and privileges, are entitled to quarterly distributions of $0.001786 per Waiver Unit and are convertible on a one-for-one basis at the option of the holder upon, among other things, payment of a quarterly cash distribution on the Common Units that has a coverage ratio of at least 1.10 and equals or exceeds the applicable distribution level: (i) Class 1 - $0.43 per Common Units; (ii) Class 2 - $0.46 per Common Unit; (iii) Class 3 - $0.49 per Common Unit; and (iv) Class 4 - $0.52 per Common Unit.  The Waiver Units will also automatically convert to Common Units - Class A upon the six-month anniversary of the occurrence of the circumstances that give rise to the right of the holder to convert.</footnote>
        <footnote id="F3">Waiver Units that have not become convertible by January 1, 2021 shall, as of the close of business on such date, automatically be cancelled.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>James E Davison</signatureName>
        <signatureDate>2010-12-30</signatureDate>
    </ownerSignature>
</ownershipDocument>
