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

    <documentType>4/A</documentType><periodOfReport>2003-11-28</periodOfReport><dateOfOriginalSubmission>2003-12-01</dateOfOriginalSubmission>
    <issuer>
        <issuerCik>0000926282</issuerCik>
        <issuerName>ADTRAN INC</issuerName>
        <issuerTradingSymbol>ADTN</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001191216</rptOwnerCik>
            <rptOwnerName>NORTH JAMES L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>ADTRAN INC.</rptOwnerStreet1>
            <rptOwnerStreet2>901 EXPLORER BOULEVARD</rptOwnerStreet2>
            <rptOwnerCity>HUNTSVILLE</rptOwnerCity>
            <rptOwnerState>AL</rptOwnerState>
            <rptOwnerZipCode>35806</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>1</isOther><otherText>Director Emeritus</otherText></reportingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDerivativeHolding><securityTitle><value>Common Stock</value></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>97000</value><footnoteId id="F1"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeHolding></nonDerivativeTable><footnotes><footnote id="F1">On December 1, 2003, the reporting person mistakenly filed a Form 4 reporting a sale of 10,000 shares of common stock that did not in fact occur.  As of November 28, 2003, the reporting person owned 97,000 shares of common stock.</footnote></footnotes><remarks/><ownerSignature><signatureName>Charlene Little, by power of attorney</signatureName><signatureDate>2004-01-09</signatureDate></ownerSignature></ownershipDocument>

