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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-04-30</periodOfReport>

    <issuer>
        <issuerCik>0000828750</issuerCik>
        <issuerName>GSI COMMERCE INC</issuerName>
        <issuerTradingSymbol>GSIC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001252005</rptOwnerCik>
            <rptOwnerName>GOLD STEPHEN J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>GSI COMMERCE, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>935 FIRST AVENUE</rptOwnerStreet2>
            <rptOwnerCity>KING OF PRUSSIA</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>19406</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2010-04-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>41056</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>27.7994</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>112385</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The filing of this Statement shall not be construed as an admission (a) that the person filing this Statement is, for the purposes of Section 16 of the Securities Exchange Act of 1934, as amended, the beneficial owner of any equity securities covered by this Statement, or (b) that this Statement is legally required to be filed by such person.</footnote>
        <footnote id="F2">This amount represents the average weighted sales price.  The highest price at which shares were sold was $28.16 and the lowest price at which shares were sold was $27.34.  Full information regarding the number of shares sold at each separate price will be provided to the SEC upon its request.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Stephen J. Gold</signatureName>
        <signatureDate>2010-05-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
