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):
                                October 23, 2003


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


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


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

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

                                 Not applicable
  ----------------------------------------------------------------------------
          (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 October 23, 2003, entitled "Cabot
                 Microelectronics Reports Results For Fourth Fiscal Quarter
                 2003."

Item 12. Results of Operations and Financial Condition.

         On October 23, 2003, Cabot Microelectronics Corporation issued a press
release entitled "Cabot Microelectronics Reports Results For Fourth Fiscal
Quarter 2003," 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 fourth fiscal quarter and fiscal year
ended September 30, 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: October 23, 2003          By: /s/ WILLIAM S. JOHNSON
                                    ----------------------
                                    William S. Johnson
                                    Vice President and Chief Financial Officer
                                    [Principal Financial Officer]






                                       2



                                INDEX TO EXHIBITS

Exhibit
Number        Title
-------       -----

99.1          Press release, dated October 23, 2003, entitled
              "Cabot Microelectronics Reports Results For Fourth Fiscal
              Quarter 2003."





                                       3