<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-06-04</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000736822</issuerCik>
        <issuerName>IMMUCOR INC</issuerName>
        <issuerTradingSymbol>BLUD</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001441124</rptOwnerCik>
            <rptOwnerName>Clouser James</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>3130 GATEWAY DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NORCROSS</rptOwnerCity>
            <rptOwnerState>GA</rptOwnerState>
            <rptOwnerZipCode>30071</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, $0.10 par value</value>
            </securityTitle>
            <transactionDate>
                <value>2009-06-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2422</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2422</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock option, right to buy</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>16.25</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2009-06-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3286</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2010-06-04</value>
            </exerciseDate>
            <expirationDate>
                <value>2015-06-04</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock, $0.10 par value</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3286</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3286</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The stock is restricted stock issued pursuant to the Companys 2005 Long Term Incentive Plan.</footnote>
        <footnote id="F2">2,422 of the total represents restricted stock which has not yet vested.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>James Clouser, by Rebecca Girod</signatureName>
        <signatureDate>2009-06-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0303
4
2009-06-04
0
0000736822
IMMUCOR INC
BLUD
0001441124
Clouser James
3130 GATEWAY DRIVE
NORCROSS
GA
30071
1
0
0
0
Common Stock, $0.10 par value
2009-06-04
4
A
0
2422
0
A
2422
D
Stock option, right to buy
16.25
2009-06-04
4
A
0
3286
0
A
2010-06-04
2015-06-04
Common Stock, $0.10 par value
3286
3286
D
The stock is restricted stock issued pursuant to the Companys 2005 Long Term Incentive Plan.
2,422 of the total represents restricted stock which has not yet vested.
James Clouser, by Rebecca Girod
2009-06-08