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

                                                                              
                         ------------------------------

                                    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 27, 2005


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

            Delaware                       000-30205                36-4324765
-------------------------------      -----------------------     ---------------
(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
          -------------------------------------------------------------
          (Former name or former address, if changed since last report)


Check the appropriate box below if the Form 8-K filing is intended to
simultaneously satisfy the filing obligation of the registrant under any of the
following provisions:

    [ ] Written communications pursuant to Rule 425 under the Securities Act 
        (17 CFR 230.425)

    [ ] Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 
        CFR 240.14a-12)

    [ ] Pre-commencement communications pursuant to Rule 14d-2(b) under the
        Exchange Act (17 CFR 240.14d-2(b))

    [ ] Pre-commencement communications pursuant to Rule 13e-4(c) under the
        Exchange Act (17 CFR 240.13e-4(c))





Item 2.02 Results of Operations and Financial Condition.

         On January 27, 2005, Cabot Microelectronics Corporation issued a press
release entitled "Cabot Microelectronics Reports Results For First Quarter of
Fiscal 2005," 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, 2004. 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 is being furnished pursuant to Item 2.02 of Form 8-K
and 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.

Item 9.01 Financial Statements and Exhibits.

         (c)      Exhibits

                  The following exhibit is being furnished, not filed, herewith
                  pursuant to Item 2.02 of Form 8-K:

                  99.1 Press release, dated January 27, 2005, entitled "Cabot
                  Microelectronics Reports Results For First Quarter of Fiscal
                  2005."





                                    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 27, 2005            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 27, 2005, entitled
                "Cabot Microelectronics Reports Results For First Quarter of
                Fiscal 2005."





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