defa14a

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A INFORMATION

PROXY STATEMENT PURSUANT TO SECTION 14(a) OF THE SECURITIES
EXCHANGE ACT OF 1934

Filed by Registrant þ

Filed by a Party other than the Registrant o

Check the appropriate box:


o	Preliminary Proxy Statement	o	Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)).

o	Definitive Proxy Statement

þ	Definitive Additional Materials

o	Soliciting Materials Pursuant to Section 240.14a-11(c) or Section 240.14a-12

CABOT MICROELECTRONICS CORPORATION

(Exact name of Registrant as Specified in Its Charter)

Payment of Filing Fee (Check the appropriate box):

	þ		No fee required.

	o		Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11.

	(1)		Title of each class of securities to which transaction applies:

(2)

Aggregate number of securities to which transaction applies:

(3)

Per unit price or other underlying value of transaction computed pursuant to Exchange Act Rule 0-11 (set forth the amount on which the filing fee is calculated and state how it was determined):

(4)

Proposed maximum aggregate value of transaction:

(5)

Total fee paid:

*** Exercise Your Right to Vote ***

IMPORTANT NOTICE Regarding the Availability of Proxy Materials
for the Shareholder Meeting to Be Held on March 8, 2011.

CABOT MICROELECTRONICS
CORPORATION

CABOT MICROELECTRONICS CORPORATION
ATTN: H. CAROL BERNSTEIN
870 N. COMMONS DRIVE
AURORA, IL 60504

Meeting Information

Meeting Type: Annual

For holders as of: January 14, 2011

Date: March 8, 2011 Time: 8:00 AM CST


Location:		Cabot Microelectronics Corporation
		870 N. Commons Drive
		Aurora, IL 60504

You are receiving this communication because you hold shares in the above named company.

This is not a ballot. You cannot use this notice to vote these shares. This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. You may view the proxy materials online at www.proxyvote.com or easily request a paper copy (see reverse side).

We encourage you to access and review all of the important information contained in the proxy materials before voting.

See the reverse side of this notice to obtain proxy materials and voting instructions.

— Before You Vote —

How to Access the Proxy Materials

Proxy Materials Available to VIEW or RECEIVE:

NOTICE AND PROXY STATEMENT ANNUAL REPORT

How to View Online:

Have the information that is printed in the box marked by the arrow è XXXX XXXX XXXX (located on the following page) and visit: www.proxyvote.com.

How to Request and Receive a PAPER or E-MAIL Copy:

If you want to receive a paper or e-mail copy of these documents, you must request one. There is NO charge for requesting a copy. Please choose one of the following methods to make your request:


1) BY INTERNET:		www.proxyvote.com
2) BY TELEPHONE:		1-800-579-1639
3) BY E-MAIL:*		sendmaterial@proxyvote.com

If requesting materials by e-mail, please send a blank e-mail with the information that is printed in the box marked by the arrow è XXXX XXXX XXXX (located on the following page) in the subject line.

Requests, instructions and other inquiries sent to this e-mail address will NOT be forwarded to your investment advisor. Please make the request as instructed above on or before February 22, 2011 to facilitate timely delivery.

— How To Vote —

Please Choose One of the Following Voting Methods

Vote In Person: Many shareholder meetings have attendance requirements including, but not limited to, the possession of an attendance ticket issued by the entity holding the meeting. Please check the meeting materials for any special requirements for meeting attendance. At the meeting, you will need to request a ballot to vote these shares.

Vote By Internet: To vote now by Internet, go to www.proxyvote.com. Have the information that is printed in the box marked by the arrow è XXXX XXXX XXXX available and follow the instructions.

Vote By Mail: You can vote by mail by requesting a paper copy of the materials, which will include a proxy card.



Voting Items


The Board of Directors recommends that you vote FOR the following:

1.		Election of Directors

		Nominees:

		01) Robert J. Birgeneau
		02) Steven V. Wilkinson
		03) Bailing Xia

The Board of Directors recommends you vote FOR the following proposal:
2.		To approve, by non-binding advisory vote, executive compensation.

The Board of Directors recommends you vote FOR THREE (3) years:
3.		To recommend, by non-binding advisory vote, the frequency of non-binding advisory executive compensation votes.

The Board of Directors recommends you vote FOR the following proposal:
4.		Ratification of the selection of PricewaterhouseCoopers LLP as the company’s independent auditors for fiscal year 2011.

NOTE: Such other business as may properly come before the meeting or any adjournment thereof.