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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 GcC2M1+M79YQTopX/E5roBTPfnDMY/zYHdMRRlN4Wsx7nTtmQjghPx/iJX3pXPFQ
 p9ZNqcl3pffO42IhnMS5XQ==

<SEC-DOCUMENT>0001319875-05-000005.txt : 20050309
<SEC-HEADER>0001319875-05-000005.hdr.sgml : 20050309
<ACCEPTANCE-DATETIME>20050309164007
ACCESSION NUMBER:		0001319875-05-000005
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20050308
FILED AS OF DATE:		20050309
DATE AS OF CHANGE:		20050309

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			MOONEY EDWARD J
		CENTRAL INDEX KEY:			0001012340

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-30205
		FILM NUMBER:		05669766

	MAIL ADDRESS:	
		STREET 1:		100 NORTH RIVERSIDE PLAZA
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CABOT MICROELECTRONICS CORP
		CENTRAL INDEX KEY:			0001102934
		STANDARD INDUSTRIAL CLASSIFICATION:	SEMICONDUCTORS & RELATED DEVICES [3674]
		IRS NUMBER:				364324765
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0930

	BUSINESS ADDRESS:	
		STREET 1:		870 NORTH COMMONS DRIVE
		CITY:			AURORA
		STATE:			IL
		ZIP:			60504
		BUSINESS PHONE:		6303755461

	MAIL ADDRESS:	
		STREET 1:		870 N COMMONS DR
		CITY:			AURORA
		STATE:			IL
		ZIP:			60504
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2005-03-08</periodOfReport>

    <noSecuritiesOwned>1</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001102934</issuerCik>
        <issuerName>CABOT MICROELECTRONICS CORP</issuerName>
        <issuerTradingSymbol>CCMP</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001012340</rptOwnerCik>
            <rptOwnerName>MOONEY EDWARD J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O CABOT MICROELECTRONICS CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>870 COMMONS DRIVE</rptOwnerStreet2>
            <rptOwnerCity>AURORA</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60504</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <footnotes></footnotes>

    <ownerSignature>
        <signatureName>H. Carol Bernstein (Power of Attorney)</signatureName>
        <signatureDate>2005-03-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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