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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,
 OPuUiZGSrjUKt/83ZFp0jmpIHX2DjupnCQsyJ43tvHGwvPjv6QHaLn6H8O2cv077
 OupuPcd8uBqn3jfXcgF8DQ==

<SEC-DOCUMENT>0001102934-03-000028.txt : 20030619
<SEC-HEADER>0001102934-03-000028.hdr.sgml : 20030619
<ACCEPTANCE-DATETIME>20030619105949
ACCESSION NUMBER:		0001102934-03-000028
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20030617
FILED AS OF DATE:		20030619

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CABOT MICROELECTRONICS CORP
		CENTRAL INDEX KEY:			0001102934
		STANDARD INDUSTRIAL CLASSIFICATION:	ABRASIVE ASBESTOS & MISC NONMETALLIC MINERAL PRODUCTS [3290]
		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

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			SKATES RONALD L
		CENTRAL INDEX KEY:			0001189841

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-30205
		FILM NUMBER:		03749694

	BUSINESS ADDRESS:	
		STREET 1:		870 N COMMONS DR
		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>4
<SEQUENCE>1
<FILENAME>c0001189841d20030619f4f.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<ownershipDocument><schemaVersion>X0101</schemaVersion>    <documentType>4</documentType><periodOfReport>2003-06-17</periodOfReport><notSubjectToSection16>0</notSubjectToSection16><issuer><issuerCik>0001102934</issuerCik><issuerName>CABOT MICROELECTRONICS CORP</issuerName>        <issuerTradingSymbol>CCMP</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId><rptOwnerCik>0001189841</rptOwnerCik><rptOwnerName>SKATES RONALD L</rptOwnerName></reportingOwnerId><reportingOwnerAddress><rptOwnerStreet1>  </rptOwnerStreet1><rptOwnerStreet2>  </rptOwnerStreet2><rptOwnerCity>  </rptOwnerCity><rptOwnerState>  </rptOwnerState><rptOwnerZipCode>  </rptOwnerZipCode></reportingOwnerAddress><reportingOwnerRelationship><isDirector>1</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle></officerTitle><otherText></otherText></reportingOwnerRelationship></reportingOwner><derivativeSecurity><securityTitle><value>Phantom Stock</value></securityTitle><conversionOrEx
ercisePrice><value>50.95</value></conversionOrExercisePrice><transactionDate><value>2003-06-17</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>J</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F1"/></transactionCoding><transactionAmounts><transactionShares><value>1513.9321</value></transactionShares><transactionValue><value>0</value></transactionValue><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2003-06-18</value></exerciseDate><expirationDate><value>2003-06-17</value><footnoteId id="F2"/></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>1513.9321</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>1513.9321</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNa
ture><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></derivativeSecurity><footnotes><footnote id="F1">Rights to acquire shares pursuant to Directors' Deferred Compensation Plan adopted March 12, 2001 as amended June 17, 2003.</footnote><footnote id="F2">Rights to aquire shares pursuant to Directors' Deferred Compensation Plan are already earned.</footnote></footnotes><ownerSignature><signatureName>Ronald L Skates</signatureName><signatureDate>2003-06-19</signatureDate></ownerSignature></ownershipDocument>

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</DOCUMENT>
</SEC-DOCUMENT>
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