<?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>0001024155</rptOwnerCik>
            <rptOwnerName>EATZ RALPH A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>P O BOX 5625</rptOwnerStreet1>
            <rptOwnerStreet2>3130 GATEWAY DR P O BOX 5625</rptOwnerStreet2>
            <rptOwnerCity>NORCROSS</rptOwnerCity>
            <rptOwnerState>GA</rptOwnerState>
            <rptOwnerZipCode>30091-5625</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CSO</officerTitle>
        </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>17399</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>322215</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>14613</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>14613</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>14613</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">33,129 of the total represents restricted stock which has not yet vested.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Ralph Eatz, 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
0001024155
EATZ RALPH A
P O BOX 5625
3130 GATEWAY DR P O BOX 5625
NORCROSS
GA
30091-5625
0
1
0
0
CSO
Common Stock, $0.10 par value
2009-06-04
4
A
0
17399
0
A
322215
D
Stock option, right to buy
16.25
2009-06-04
4
A
0
14613
0
A
2010-06-04
2015-06-04
Common Stock, $0.10 par value
14613
14613
D
The stock is restricted stock issued pursuant to the Companys 2005 Long Term Incentive Plan.
33,129 of the total represents restricted stock which has not yet vested.
Ralph Eatz, by Rebecca Girod
2009-06-08