<?xml version="1.0"?><ownershipDocument>
    <schemaVersion>X0101</schemaVersion>

    <documentType>4</documentType><periodOfReport>2003-07-01</periodOfReport>
    <issuer>
        <issuerCik>0000918999</issuerCik>
        <issuerName>DT INDUSTRIES INC</issuerName>
        <issuerTradingSymbol>dtii</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId>
            <rptOwnerCik>0001181321</rptOwnerCik>
            <rptOwnerName>LANNERT ROBERT C</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle></officerTitle><otherText></otherText></reportingOwnerRelationship></reportingOwner><derivativeSecurity><securityTitle><value>Stock Equivalent Units</value><footnoteId id="F1" /></securityTitle><conversionOrExercisePrice><value>0</value><footnoteId id="F1" /></conversionOrExercisePrice><transactionDate><value>2003-07-01</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>J</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F1" /></transactionCoding><transactionTimeliness><value></value></transactionTimeliness><transactionAmounts><transactionShares><value>1744.186</value><footnoteId id="F2" /></transactionShares><transactionValue><value>2.15</value></transactionValue><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>1988-08-08</value><footnoteId id="F1" /></exerciseDate><expirationDate><value>1988-08-08</value><footnoteId id="F1" /></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>1744.186</value><footnoteId id="F2" /></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>21349.013</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership></ownershipNature></derivativeSecurity><footnotes><footnote id="F1">A right granted under the Issuer's Directors Deferred Compensation Plan to receive a cash payment upon retirement, death or termination of service as a Director, the amount of which is equal to the reported trading price of the underlying securities.</footnote><footnote id="F2">Stock Equivalent Units acquired through deferral of compensation pursuant to the Directors Deferred Compensation Plan.</footnote></footnotes><ownerSignature><signatureName>Dennis S. Dockins
Attorney-in-fact</signatureName><signatureDate>2003-07-03</signatureDate></ownerSignature></ownershipDocument>

