-----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,
 F3rp9aVbahaGpWtZCBGUDDM/KIGtMOKiNx5x01jHRYD8kwIlbSvNuxs+/2gRMPip
 pVIXI4+fHQMYvqdGkLPTdQ==

<SEC-DOCUMENT>0000945436-09-000065.txt : 20090303
<SEC-HEADER>0000945436-09-000065.hdr.sgml : 20090303
<ACCEPTANCE-DATETIME>20090303160729
ACCESSION NUMBER:		0000945436-09-000065
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20090227
FILED AS OF DATE:		20090303
DATE AS OF CHANGE:		20090303

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			CABRERA MIGNON
		CENTRAL INDEX KEY:			0001374133

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-13828
		FILM NUMBER:		09651735

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		636-474-5000

	MAIL ADDRESS:	
		STREET 1:		501 PEARL DRIVE
		CITY:			ST PETERS
		STATE:			MO
		ZIP:			63376

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MEMC ELECTRONIC MATERIALS INC
		CENTRAL INDEX KEY:			0000945436
		STANDARD INDUSTRIAL CLASSIFICATION:	SEMICONDUCTORS & RELATED DEVICES [3674]
		IRS NUMBER:				561505767
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		501 PEARL DRIVE
		STREET 2:		P. O. BOX 8
		CITY:			ST. PETERS
		STATE:			MO
		ZIP:			63376
		BUSINESS PHONE:		6364745000

	MAIL ADDRESS:	
		STREET 1:		501 PEARL DRIVE
		STREET 2:		P. O. BOX 8
		CITY:			ST. PETERS
		STATE:			MO
		ZIP:			63376
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-02-27</periodOfReport>

    <issuer>
        <issuerCik>0000945436</issuerCik>
        <issuerName>MEMC ELECTRONIC MATERIALS INC</issuerName>
        <issuerTradingSymbol>WFR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001374133</rptOwnerCik>
            <rptOwnerName>CABRERA MIGNON</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O MEMC ELECTRONIC MATERIALS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>P.O. BOX 8</rptOwnerStreet2>
            <rptOwnerCity>ST. PETERS,</rptOwnerCity>
            <rptOwnerState>MO</rptOwnerState>
            <rptOwnerZipCode>63376</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>SVP Human Resources</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-02-27</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>488</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>13.64</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4374</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Surrender of shares in payment of tax withholding due as a result of the vesting of RSUs granted in accordance with Rule 16b-3.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Mignon Cabrera</signatureName>
        <signatureDate>2009-03-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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