-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 Bir3UYjVP+wnPnrkOElefP0YLlAbdgN0T0J2/BoRWm04hR4eKnpqHqtiFRuwIqOz
 RjwvO50mCof4H1oRYx4uGw==

<SEC-DOCUMENT>0000090185-06-000065.txt : 20060504
<SEC-HEADER>0000090185-06-000065.hdr.sgml : 20060504
<ACCEPTANCE-DATETIME>20060504123436
ACCESSION NUMBER:		0000090185-06-000065
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20060503
FILED AS OF DATE:		20060504
DATE AS OF CHANGE:		20060504

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			SIGMA ALDRICH CORP
		CENTRAL INDEX KEY:			0000090185
		STANDARD INDUSTRIAL CLASSIFICATION:	WHOLESALE-CHEMICALS & ALLIED PRODUCTS [5160]
		IRS NUMBER:				431050617
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		3050 SPRUCE ST
		CITY:			ST LOUIS
		STATE:			MO
		ZIP:			63103
		BUSINESS PHONE:		3147715765

	MAIL ADDRESS:	
		STREET 1:		3050 SPRUCE STREET
		CITY:			ST LOUIS
		STATE:			MO
		ZIP:			63103

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	SIGMA INTERNATIONAL LTD
		DATE OF NAME CHANGE:	19750925

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ALDRICH CHEMICAL CO INC
		DATE OF NAME CHANGE:	19750908

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			HARVEY DAVID R
		CENTRAL INDEX KEY:			0001201182

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-08135
		FILM NUMBER:		06807095

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		3147715765

	MAIL ADDRESS:	
		STREET 1:		3050 SPRUCE STREET
		CITY:			ST LOUIS
		STATE:			MO
		ZIP:			63103
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-05-03</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000090185</issuerCik>
        <issuerName>SIGMA ALDRICH CORP</issuerName>
        <issuerTradingSymbol>SIAL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001201182</rptOwnerCik>
            <rptOwnerName>HARVEY DAVID R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>3050 SPRUCE STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>ST LOUIS</rptOwnerCity>
            <rptOwnerState>MO</rptOwnerState>
            <rptOwnerZipCode>63103</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, $1 Par Value</value>
            </securityTitle>
            <transactionDate>
                <value>2006-05-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>7300</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>36.5</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>50490</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, $1 Par Value</value>
            </securityTitle>
            <transactionDate>
                <value>2006-05-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>7300</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>69</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>43190</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option, Right to Buy</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>36.5</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2006-05-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>7300</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>36.5</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2001-11-13</value>
            </exerciseDate>
            <expirationDate>
                <value>2010-11-13</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock, $1 Par Value</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>7300</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2700</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <ownerSignature>
        <signatureName>Debbie Bockius, Attorney in Fact</signatureName>
        <signatureDate>2006-05-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----