<SUBMISSION>
<ACCESSION-NUMBER>0001238550-07-000017
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20070524
<FILING-DATE>20070529
<DATE-OF-FILING-DATE-CHANGE>20070529
<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 L DOUGLAS
<CIK>0001103699
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-13646
<FILM-NUMBER>07884507
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>C/O LIPPERT COMPONENTS
<STREET2>2375 TAMIAMI TRAIL NORTH, SUITE 110
<CITY>NAPLES
<STATE>FL
<ZIP>34103
<PHONE>9416592005
</BUSINESS-ADDRESS>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
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            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>851752</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2007-05-25</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>322</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>33.63</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>851430</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>127620</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">As trustee for the trusts for the benefit of members of Mr. Lippert's family, over which Mr. Lippert has sole voting and dispositive powers.</footnote>
        <footnote id="F2">Includes an administrative adjustment of 163 shares.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Fredric M. Zinn, on behalf of L. Douglas Lippert</signatureName>
        <signatureDate>2007-05-29</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
