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

    <documentType>4</documentType><periodOfReport>2004-01-07</periodOfReport>
    <issuer>
        <issuerCik>0000879526</issuerCik>
        <issuerName>WABASH NATIONAL CORP /DE</issuerName>
        <issuerTradingSymbol>WNC</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001187262</rptOwnerCik>
            <rptOwnerName>JISCHKE MARTIN C</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1000 SAGAMORE PARKWAY SOUTH</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>LAFAYETTE</rptOwnerCity>
            <rptOwnerState>IN</rptOwnerState>
            <rptOwnerZipCode>47905</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther></reportingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Common Stock</value><footnoteId id="F1"/></securityTitle><transactionDate><value>2004-01-07</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>1000</value></transactionShares><transactionPricePerShare><value>29.30</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>6063</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeTransaction></nonDerivativeTable><footnotes><footnote id="F1">RESTRICTIONS: Grants will vest one-half vests January 7, 2005, remaining half vests January 7, 2006</footnote></footnotes><remarks/><ownerSignature><signatureName>Cynthia Kretz</signatureName><signatureDate>2004-01-07</signatureDate></ownerSignature></ownershipDocument>

