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

    <documentType>4</documentType><periodOfReport>2003-07-09</periodOfReport>
    <issuer>
        <issuerCik>0000912603</issuerCik>
        <issuerName>SCHNITZER STEEL INDUSTRIES INC</issuerName>
        <issuerTradingSymbol>SCHN</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId>
            <rptOwnerCik>0001032738</rptOwnerCik>
            <rptOwnerName>PHILIP ROBERT W</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>1</isTenPercentOwner><isOther>0</isOther><officerTitle>President</officerTitle></reportingOwnerRelationship></reportingOwner><reportingOwner><reportingOwnerId>
            <rptOwnerCik>0001249504</rptOwnerCik>
            <rptOwnerName>PHILIP RITA S</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>1</isTenPercentOwner><isOther>0</isOther></reportingOwnerRelationship></reportingOwner><nonDerivativeSecurity><securityTitle><value>Class A Common Stock</value></securityTitle><transactionDate><value>2003-07-09</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>10599</value></transactionShares><transactionValue><value>12.00</value></transactionValue><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>10599</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeSecurity><nonDerivativeSecurity><securityTitle><value>Class A Common Stock</value></securityTitle><transactionDate><value>2003-07-09</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>385</value></transactionShares><transactionValue><value>18.50</value></transactionValue><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>10984</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeSecurity><nonDerivativeSecurity><securityTitle><value>Class A Common Stock</value></securityTitle><transactionDate><value>2003-07-09</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>S</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>6000</value></transactionShares><transactionValue><value>47.08</value></transactionValue><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>4984</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeSecurity><nonDerivativeSecurity><securityTitle><value>Class A Common Stock</value></securityTitle><transactionDate><value>2003-07-09</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>S</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>4984</value></transactionShares><transactionValue><value>47.124</value></transactionValue><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>0</value><footnoteId id="F1"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeSecurity><derivativeSecurity><securityTitle><value>Option to Buy</value></securityTitle><conversionOrExercisePrice><value>12.00</value></conversionOrExercisePrice><transactionDate><value>2003-07-09</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>10599</value></transactionShares><transactionValue><value>0</value></transactionValue><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2000-04-13</value></exerciseDate><expirationDate><value>2009-04-13</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Class A Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>10599</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>0</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeSecurity><derivativeSecurity><securityTitle><value>Option to Buy</value></securityTitle><conversionOrExercisePrice><value>18.50</value></conversionOrExercisePrice><transactionDate><value>2003-07-09</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>385</value></transactionShares><transactionValue><value>0</value></transactionValue><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>1995-06-01</value><footnoteId id="F2"/></exerciseDate><expirationDate><value>2004-06-01</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Class A Common Stocl</value></underlyingSecurityTitle><underlyingSecurityShares><value>385</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>16121</value><footnoteId id="F3"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeSecurity><footnotes><footnote id="F1">The reporting person has indirect beneficial ownership of 1,050 shares of Class A Common Stock, held by Robert W. Philip, as custodian under Oregon Uniform Transfers to Minors Act, F/B/O Joshua Henry Philip.</footnote><footnote id="F2">The option was granted for 17,506 shares on 6/1/94 and became exercisable for 20% of the shares on each of the first five anniversaries of the grant date.</footnote><footnote id="F3">The reporting person has indirect beneficial ownership of Class B Common Stock, which is immediately convertible on a one-for-one basis into Class A Common Stock and has no expiration date.  The reporting person's Class B Common Stock ownership is as follows:  126,700 shares, represented by voting trust certificates held by Rita S. Philip and Robert W. Philip, as Co-Trustees under Trust Agreement with Rita S. Philip dated 4/21/93; 16,458 shares, represented by voting trust certificates held by Rita S. Philip, Family Trustee, and Jill Schnitzer Edelson, Independent Trustee, U/A/D December 22, 1994, F/B/O Joshua Henry Philip; and 8,131 shares, represented by voting trust certificates held by Rita S. Philip, Family Trustee, and Jill Schnitzer Edelson, Independent Trustee, U/A/D December 22, 1994, F/B/O Bichele Babette Philip.</footnote></footnotes><ownerSignature><signatureName>Charles A. Ford, Attorney-In-Fact</signatureName><signatureDate>2003-07-10</signatureDate></ownerSignature></ownershipDocument>

