UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

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                                    FORM 8-K


              Current Report Pursuant to Section 13 or 15(d) of the
                         Securities Exchange Act of 1934


                Date of Report (date of earliest event reported):
                                January 22, 2004


                       Cabot Microelectronics Corporation
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             (Exact name of registrant as specified in its charter)


           Delaware                      000-30205                 36-4324765
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(State or other jurisdiction of    (Commission File Number)       (IRS Employer
        incorporation)                                           Identification)


                    870 Commons Drive, Aurora, Illinois 60504
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               (Address of principal executive offices) (Zip Code)

                                 (630) 375-6631
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              (Registrant's telephone number, including area code)

                                 Not applicable
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          (Former name or former address, if changed since last report)





Item 7. Financial Statements and Exhibits.

          (c)  Exhibits

               The following exhibits are filed herewith:

               99.1 Press release, dated January 22, 2004, entitled "Cabot
               Microelectronics Reports Results For First Fiscal Quarter 2004."

Item 12. Results of Operations and Financial Condition.

           On January 22, 2004, Cabot Microelectronics Corporation issued a
press release entitled "Cabot Microelectronics Reports Results For First Fiscal
Quarter 2004," a copy of which is attached hereto as Exhibit 99.1 and
incorporated herein by reference. The press release contains financial and other
information including that related to our first fiscal quarter ended December
31, 2003. The press release also includes cautionary statements identifying
important factors that could cause actual results to differ materially from
those described by any forward-looking statements. This information shall not be
deemed "filed" for purposes of Section 18 of the Securities and Exchange Act of
1934, as amended (the "Exchange Act"), or incorporated by reference in any
filing under the Securities Act of 1933, as amended, or the Exchange Act, except
as shall be expressly set forth by specific reference in such a filing.



                                    SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.


                                       CABOT MICROELECTRONICS CORPORATION


Date: January 22, 2004                 By: /s/ WILLIAM S. JOHNSON
                                           ----------------------
                                           William S. Johnson
                                           Vice President and Chief Financial
                                           Officer [Principal Financial Officer]



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                               INDEX TO EXHIBITS

Exhibit
Number                 Title



99.1                   Press release, dated January 22, 2004, entitled
                       "Cabot Microelectronics Reports Results For First
                       Fiscal Quarter 2004."






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