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

    <documentType>4</documentType><periodOfReport>2003-12-11</periodOfReport>
    <issuer>
        <issuerCik>0000920354</issuerCik>
        <issuerName>MRO SOFTWARE INC</issuerName>
        <issuerTradingSymbol>MROI</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000948839</rptOwnerCik>
            <rptOwnerName>DANIELS ROBERT L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O MRO SOFTWARE, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>100 CROSBY DRIVE</rptOwnerStreet2>
            <rptOwnerCity>BEDFORD</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>01730</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>1</isTenPercentOwner><isOther>0</isOther></reportingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Common Stock, $ .01 par value</value></securityTitle><transactionDate><value>2003-12-11</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>S</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>7200</value></transactionShares><transactionPricePerShare><value>13.3384</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>3120955</value><footnoteId id="F1"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value><footnoteId id="F1"/></directOrIndirectOwnership><natureOfOwnership><value/><footnoteId id="F1"/></natureOfOwnership></ownershipNature></nonDerivativeTransaction></nonDerivativeTable><footnotes><footnote id="F1">Represents shares held by the Reporting Person, individually, and includes 72,700 shares held by the Reporting Person's spouse, and 19,800 shares which are held for the benefit of his minor children; does not include any shares held by his former spouse or his adult children.  The Reporting Person disclaims beneficial ownership of all shares not held by him, individually.</footnote></footnotes><remarks/><ownerSignature><signatureName>Robert L. Daniels</signatureName><signatureDate>2003-12-15</signatureDate></ownerSignature></ownershipDocument>

