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

    <schemaVersion>X0304</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2011-08-19</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001297177</rptOwnerCik>
            <rptOwnerName>FLYNT RICHARD A JR</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>3130 GATEWAY DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NORCROSS</rptOwnerCity>
            <rptOwnerState>GA</rptOwnerState>
            <rptOwnerZipCode>30091</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>SVP and CFO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>26.9</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2011-08-19</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>U</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>21657</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2011-08-19</value>
            </exerciseDate>
            <expirationDate>
                <value>2011-08-19</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>21657</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">On August 19, 2011, IVD Acquisition Corporation, an affiliate of TPG Capital, purchased in a tender offer the outstanding shares of common stock, including the associated common stock purchase rights (restricted stock awards, restricted stock units, performance stock units and options) of Immucor at a price of $27.00 per share, in cash, payable without interest and less any applicable withholding taxes.  This transaction is more fully described in the Schedule 14D-9 filed with the SEC on July 5, 2011 and subsequently amended.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Richard A Flynt, by Rebecca Girod</signatureName>
        <signatureDate>2011-08-25</signatureDate>
    </ownerSignature>
</ownershipDocument>
[{"type": "4", "sequence": "1", "filename": "primary_doc.xml", "description": "PRIMARY DOCUMENT", "secsgml_size_bytes": 4279}]
X0304
4
2011-08-19
1
0000736822
IMMUCOR INC
BLUD
0001297177
FLYNT RICHARD A JR
3130 GATEWAY DRIVE
NORCROSS
GA
30091
0
1
0
0
SVP and CFO
Stock option (right to buy)
26.9
2011-08-19
4
U
0
21657
D
2011-08-19
2011-08-19
Common Stock
21657
0
D
On August 19, 2011, IVD Acquisition Corporation, an affiliate of TPG Capital, purchased in a tender offer the outstanding shares of common stock, including the associated common stock purchase rights (restricted stock awards, restricted stock units, performance stock units and options) of Immucor at a price of $27.00 per share, in cash, payable without interest and less any applicable withholding taxes.  This transaction is more fully described in the Schedule 14D-9 filed with the SEC on July 5, 2011 and subsequently amended.
Richard A Flynt, by Rebecca Girod
2011-08-25