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

    <documentType>4</documentType><periodOfReport>2004-01-14</periodOfReport>
    <issuer>
        <issuerCik>0000912603</issuerCik>
        <issuerName>SCHNITZER STEEL INDUSTRIES INC</issuerName>
        <issuerTradingSymbol>SCHN</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001249502</rptOwnerCik>
            <rptOwnerName>NYE DANIELLE EASLY</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>3200 NW YEON AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>PORTLAND</rptOwnerCity>
            <rptOwnerState>OR</rptOwnerState>
            <rptOwnerZipCode>97210</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>1</isTenPercentOwner><isOther>0</isOther></reportingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Class A Common Stock</value></securityTitle><transactionDate><value>2004-01-14</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>C</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>5000</value></transactionShares><transactionPricePerShare><value>0</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>5000</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>By Voting Trust</value></natureOfOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeTransaction><securityTitle><value>Class A Common Stock</value></securityTitle><transactionDate><value>2004-01-14</value></transactionDate><transactionCoding><transactionFormType>5</transactionFormType><transactionCode>Z</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>5000</value></transactionShares><transactionPricePerShare><value>0</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>0</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>By Voting Trust</value></natureOfOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeTransaction><securityTitle><value>Class A Common Stock</value></securityTitle><transactionDate><value>2004-01-14</value></transactionDate><transactionCoding><transactionFormType>5</transactionFormType><transactionCode>Z</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>5000</value></transactionShares><transactionPricePerShare><value>0</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>5000</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeTransaction></nonDerivativeTable><derivativeTable><derivativeTransaction><securityTitle><value>Class B Common Stock</value></securityTitle><conversionOrExercisePrice><footnoteId id="F1"/></conversionOrExercisePrice><transactionDate><value>2004-01-14</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>C</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>5000</value></transactionShares><transactionPricePerShare><value>0</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><footnoteId id="F1"/></exerciseDate><expirationDate><footnoteId id="F1"/></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Class A Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>5000</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>60502</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>By Voting Trust</value></natureOfOwnership></ownershipNature></derivativeTransaction><derivativeHolding><securityTitle><value>Class B Common Stock</value></securityTitle><conversionOrExercisePrice><footnoteId id="F1"/></conversionOrExercisePrice><exerciseDate><footnoteId id="F1"/></exerciseDate><expirationDate><footnoteId id="F1"/></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Class A Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>8516</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>8516</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>By Voting Trust</value><footnoteId id="F2"/></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Class B Common Stock</value></securityTitle><conversionOrExercisePrice><footnoteId id="F1"/></conversionOrExercisePrice><exerciseDate><footnoteId id="F1"/></exerciseDate><expirationDate><footnoteId id="F1"/></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Class A Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>1250</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>1250</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>By Voting Trust</value><footnoteId id="F3"/></natureOfOwnership></ownershipNature></derivativeHolding></derivativeTable><footnotes><footnote id="F1">Class B Common Stock is immediately convertible on a one-for-one basis into Class A Common Stock and has no expiration date.</footnote><footnote id="F2">Voting trust certificates are held by Danielle Easly Nye, Family Trustee and David Easly, Independent Trustee U/A/D December 27, 1999 F/B/O Vivian E. Nye</footnote><footnote id="F3">Voting trust certificates are held by Danielle Easly Nye, Family Trustee and David Easly, Independent Trustee U/A/D December 20, 2002 F/B/O Maximus E. Nye</footnote></footnotes><remarks/><ownerSignature><signatureName>Charles A Ford, Attorney-In-Fact</signatureName><signatureDate>2004-01-15</signatureDate></ownerSignature></ownershipDocument>

