<SUBMISSION>
<ACCESSION-NUMBER>0001238550-07-000023
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20070601
<FILING-DATE>20070605
<DATE-OF-FILING-DATE-CHANGE>20070605
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>DREW INDUSTRIES INC
<CIK>0000763744
<ASSIGNED-SIC>3714
<IRS-NUMBER>133250533
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>200 MAMARONECK AVE
<CITY>WHITE PLAINS
<STATE>NY
<ZIP>10601
<PHONE>9144289098
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>200 MAMARONECK AVE
<CITY>WHITE PLAINS
<STATE>NY
<ZIP>10601
</MAIL-ADDRESS>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>LIPPERT JASON
<CIK>0001238361
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-13646
<FILM-NUMBER>07902162
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>C/O LIPPERT COMPONENTS INC
<STREET2>2375 TAMIAMI TRAIL NORTH STE 11
<CITY>NAPLES
<STATE>FL
<ZIP>34103
</MAIL-ADDRESS>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2007-06-01</periodOfReport>

    <issuer>
        <issuerCik>0000763744</issuerCik>
        <issuerName>DREW INDUSTRIES INC</issuerName>
        <issuerTradingSymbol>DW</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001238361</rptOwnerCik>
            <rptOwnerName>LIPPERT JASON</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O LIPPERT COMPONENTS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>2766 COLLEGE AVENUE</rptOwnerStreet2>
            <rptOwnerCity>GOSHEN</rptOwnerCity>
            <rptOwnerState>IN</rptOwnerState>
            <rptOwnerZipCode>46528</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>President / CEO of Subsidiary</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2007-06-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>87620</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>190658</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Shares held by L. Douglas Lippert as Trustee of a trust for the benefit of Jason D. Lippert, his son, were transferred to Jason D. Lippert in accordance with the terms of the trust.  As trustee, L. Douglas Lippert had sole voting and dispositive power over such shares, but disclaimed beneficial ownership thereof.  As a result of the transfer of such shares, Jason D. Lippert has sole voting and dispositive power over such shares in addition to beneficial ownership thereof.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Fredric M. Zinn on behalf of Jason Lippert</signatureName>
        <signatureDate>2007-06-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
