AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON APRIL 7, 2000
                                              REGISTRATION NO. 333-________
===========================================================================
                     SECURITIES AND EXCHANGE COMMISSION
                           WASHINGTON, D.C. 20549
                    -----------------------------------

                                  FORM S-8

                           REGISTRATION STATEMENT
                                   UNDER
                         THE SECURITIES ACT OF 1933

                    -----------------------------------
                     CABOT MICROELECTRONICS CORPORATION
           (Exact name of registrant as specified in its charter)

         DELAWARE                                           36-4324765
     (State or other                                     (I.R.S. Employer
     jurisdiction of                                  Identification Number)
     incorporation or
      organization)

                          870 NORTH COMMONS DRIVE
                           AURORA, ILLINOIS 60504
           (Address of registrant's principal executive offices)

      CABOT MICROELECTRONICS CORPORATION EMPLOYEE STOCK PURCHASE PLAN
                          (Full title of the plan)


                              MATTHEW NEVILLE
                   PRESIDENT AND CHIEF EXECUTIVE OFFICER
                     CABOT MICROELECTRONICS CORPORATION
                          870 NORTH COMMONS DRIVE
                           AURORA, ILLINOIS 60504
                               (630) 375-6631
         (Name, address, and telephone number of agent for service)

                      CALCULATION OF REGISTRATION FEE

==============================================================================
                                     PROPOSED      PROPOSED
                         AMOUNT TO    MAXIMUM       MAXIMUM
                            BE        OFFERING     AGGREGATE        AMOUNT OF
TITLE OF SECURITIES     REGISTERED   PRICE PER      OFFERING      REGISTRATION
 TO BE REGISTERED           (1)      SHARE (2)     PRICE (2)           FEE
------------------------------------------------------------------------------
Common Stock, par value   475,000    $25.25       $11,993,750.00    $3,167.00
$.001 per share (3)       shares
------------------------------------------------------------------------------

(1)  Plus such additional  number of shares as may be required in the event
     of a stock dividend,  stock split,  recapitalization  or other similar
     event in accordance  with Rule 416 of the  Securities  Act of 1933, as
     amended (the "Securities Act").

(2)  Estimated  solely for the purpose of determining the  registration fee
     pursuant to Rule 457(h) of the Securities Act.

(3)  Includes the Rights associated with the Common Stock.


<PAGE>
                                   PART I

                              EXPLANATORY NOTE

     This Form S-8  Registration  Statement  relates to  475,000  shares of
common  stock of Cabot  Microelectronics  Corporation,  par value $.001 per
share (the "Common  Stock"),  which may be issued under our Employee  Stock
Purchase Plan (the "ESPP").

     The  documents  containing  information  specified  by  Part I of this
Registration  Statement have been or will be sent or given to  participants
in the ESPP as specified in Rule  428(b)(1)  promulgated  by the Securities
and  Exchange  Commission  (the  "SEC")  under  the  Securities  Act.  Such
document(s) are not required to be filed with the SEC but constitute (along
with  the  documents  incorporated  by  reference  into  this  Registration
Statement pursuant to Item 3 of Part II hereof) a prospectus that meets the
requirements of Section 10(a) of the Securities Act.

     References  to  the  "Company"   shall  mean  Cabot   Microelectronics
Corporation, a Delaware corporation.

                                  PART II

             INFORMATION REQUIRED IN THE REGISTRATION STATEMENT


     ITEM 3. INCORPORATION OF DOCUMENTS BY REFERENCE

     We file annual,  quarterly and special  reports,  proxy statements and
other  information with the SEC. You may read and copy any document we file
at the SEC's public  reference rooms in Washington,  D.C., New York, NY and
Chicago,  IL. Please call the SEC at 1-800-SEC-0330 for further information
on the public  reference  rooms.  Our SEC filings are also available to the
public from the SEC's web site at  http://www.sec.gov.  Reports,  proxy and
information  statements  and other  information  concerning  us can also be
inspected at the offices of the Nasdaq Stock Market's  National Market,  33
Whitehall Street, New York, NY 10004.

     The SEC allows us to "incorporate by reference"  information into this
Registration  Statement,   which  means  that  we  can  disclose  important
information to you by referring you to another  document  filed  separately
with the SEC. The information incorporated by reference is considered to be
part of this  Registration  Statement,  and later  information that we file
with the SEC will  automatically  update this  Registration  Statement.  We
incorporate  by reference  the following  documents and any future  filings
made  with  the  SEC  under  Sections  13(a),  13(c),  14 or  15(d)  of the
Securities  Exchange Act of 1934, as amended (the "Exchange Act"), prior to
the termination of the offering:

     (a)  Our  prospectus  filed with the SEC on April 4, 2000  pursuant to
          Rule 424(b) of the  Securities  Act in  connection  with the Form
          S-1,  which  includes our audited  financial  statements  for the
          fiscal year ended  September  30, 1999 and describes the terms of
          the Common Stock.

     (b)  Our  Registration  Statement  of Form 8-A  filed  with the SEC on
          April 3, 2000, which describes the terms of the Common Stock.


     ITEM 4. DESCRIPTION OF SECURITIES

     Not applicable.


     ITEM 5. INTERESTS OF NAMED EXPERTS AND COUNSEL

     Fried,  Frank,  Harris,  Shriver & Jacobson (a  partnership  including
professional corporations), New York, New York, will pass upon the validity
of the issuance of the shares of Common Stock.


     ITEM 6. INDEMNIFICATION OF DIRECTORS AND OFFICERS

     Section  145 of the  Delaware  General  Corporation  Law (the  "DGCL")
provides that a corporation may indemnify directors and officers as well as
other  employees and individuals  against  expenses  (including  attorneys'
fees),  judgments,  fines and amounts paid in settlement in connection with
specified  actions,   suits  and  proceedings,   whether  civil,  criminal,
administrative,  or investigative  (other than an action by or in the right
of the corporation -- a "derivative  action"),  if they acted in good faith
and in a manner  they  reasonably  believed  to be in or not opposed to the
best interests of the corporation  and, with respect to any criminal action
or  proceeding,  had no  reasonable  cause to  believe  their  conduct  was
unlawful.  A  similar  standard  is  applicable  in the case of  derivative
actions,  except that  indemnification  only extends to expenses (including
attorneys'  fees) incurred in connection  with the defense or settlement of
such action,  and the statute  requires court approval  before there can be
any indemnification where the person seeking indemnification has been found
liable to the corporation. The statute provides that it is not exclusive of
other indemnification that may be granted by a corporation's certificate of
incorporation,  bylaws,  disinterested  director  vote,  stockholder  vote,
agreement, or otherwise.

     Our  bylaws  and  our  certificate  of  incorporation  require  us  to
indemnify to the fullest  extent  authorized by the DGCL any person made or
threatened  to be made a party to an action,  suit or  proceeding,  whether
criminal,  civil,  administrative or  investigative,  by reason of the fact
that he or she is or was a director or officer of the Company, or is or was
serving at the request of the Company as a director,  officer,  employee or
agent of another corporation or of a partnership,  joint venture,  trust or
other enterprise.

     As permitted  by section  102(b)(7) of the DGCL,  our  certificate  of
incorporation  eliminates the liability of a director to the corporation or
its  stockholders for monetary damages for such breach of fiduciary duty as
a  director,  except  for  liabilities  arising  (a) from any breach of the
director's duty of loyalty to the corporation or its stockholders; (b) from
acts or omissions not in good faith or which involve intentional misconduct
or a knowing  violation of law; (c) under  section 174 of the DGCL;  or (d)
from any transaction from which the director  derived an improper  personal
benefit.

     We intend to obtain primary and excess insurance policies insuring our
directors  and  officers  and  those of our  subsidiaries  against  certain
liabilities  they may incur in their  capacity as directors  and  officers.
Under these policies,  the insurer, on our behalf, may also pay amounts for
which we have granted indemnification to the directors or officers.

     Additionally, reference is made to the Underwriting Agreement filed as
Exhibit 1.1 to our Registration  Statement No. 333-95093 on Form S-1, which
provides for  indemnification  by our  underwriters,  their  directors  and
officers who sign the  registration  statement  and persons who control us,
under certain circumstances.


     ITEM 7. EXEMPTION FROM REGISTRATION CLAIMED

     Not applicable.


     ITEM 8. EXHIBITS

EXHIBIT NO.             DESCRIPTION OF EXHIBIT
-----------             ----------------------

4.1                     Form of Certificate of Incorporation of the Company
                        previously  filed as Exhibit  3.1 to the  Company's
                        Registration  Statement No.  333-95093 on Form S-1,
                        and incorporated herein by reference

4.2                     Form of By-Laws of the Company  previously filed as
                        Exhibit 3.2 to the Company's Registration Statement
                        No. 333-95093 on Form S-1, and incorporated  herein
                        by reference

4.3                     Form of Cabot Microelectronics Corporation Employee
                        Stock  Purchase Plan,  previously  filed as Exhibit
                        10.15 to the Company's  Registration  Statement No.
                        333-95093 on Form S-1, and  incorporated  herein by
                        reference

5.1*                    Opinion of Fried, Frank, Harris, Shriver & Jacobson

23.1                    Consent of Fried, Frank, Harris, Shriver & Jacobson
                        (included in Exhibit 5.1)

23.2*                   Consent of PricewaterhouseCoopers  LLP (independent
                        public accountants)

-------------------------
*    Filed herewith.


     ITEM 9. UNDERTAKINGS

     The Company hereby undertakes:

          (a) To file, during any period in which offers or sales are being
     made, a post-effective amendment to this Registration Statement:

               (i) To include any prospectus  required by Section  10(a)(3)
          of the Securities Act;

               (ii) To  reflect  in the  prospectus  any  facts  or  events
          arising after the effective date of this  Registration  Statement
          (or the most  recent  post-effective  amendment  thereof)  which,
          individually or in the aggregate,  represent a fundamental change
          in the information set forth in this Registration Statement;

               (iii) To include any  material  information  with respect to
          the  plan  of  distribution  not  previously  disclosed  in  this
          Registration Statement or any material change to such information
          in this Registration Statement;

     provided,  however,  that  paragraphs (i) and (ii) do not apply if the
     information  required to be included in a post-effective  amendment by
     those  paragraphs  is  contained  in  periodic  reports  filed with or
     furnished to the SEC by the Company  pursuant to Section 13 or Section
     15(d) of the Exchange Act that are  incorporated  by reference in this
     Registration Statement.

          (b) That, for the purpose of determining  any liability under the
     Securities Act, each such post-effective  amendment shall be deemed to
     be a new  registration  statement  relating to the securities  offered
     therein,  and the  offering of such  securities  at that time shall be
     deemed to be the initial bona fide offering thereof.

          (c) To  remove  from  registration  by means of a  post-effective
     amendment any of the securities  being  registered which remain unsold
     at the termination of the offering.

          (d) That, for the purpose of determining  any liability under the
     Securities Act, each filing of the Company's annual report pursuant to
     Section   13(a)  or  Section   15(d)  of  the  Exchange  Act  that  is
     incorporated  by reference  in this  Registration  Statement  shall be
     deemed to be a new registration  statement  relating to the securities
     offered  therein,  and the  offering of such  securities  at that time
     shall be deemed to be the initial bona fide offering thereof.

     Insofar  as   indemnification   for  liabilities   arising  under  the
Securities  Act may be permitted  to  directors,  officers and  controlling
persons of the Company  pursuant to the  provisions  described in Item 6 of
this  Registration  Statement,  or otherwise,  the Company has been advised
that in the  opinion  of the SEC such  indemnification  is  against  public
policy as expressed in the Securities Act and is, therefore, unenforceable.
In the event  that a claim for  indemnification  against  such  liabilities
(other than the  payment by the  Company of expenses  incurred or paid by a
director,  officer or  controlling  person of the Company in the successful
defense of any action,  suit or  proceeding)  is asserted by such director,
officer or  controlling  person in  connection  with the  securities  being
registered,  the  Company  will,  unless in the  opinion of its counsel the
matter has been  settled  by  controlling  precedent,  submit to a court of
appropriate jurisdiction the question whether such indemnification by it is
against  public  policy  as  expressed  in the  Securities  Act and will be
governed by the final adjudication of such issue.


<PAGE>


                                 SIGNATURES

     Pursuant to the  requirements  of the  Securities  Act, the Registrant
certifies  that it has  reasonable  grounds to believe that it meets all of
the  requirements  for  filing  on  Form  S-8  and  has  duly  caused  this
Registration  Statement  to be  signed on its  behalf  by the  undersigned,
thereunto duly  authorized,  in the city of Aurora,  State of Illinois,  on
April 7, 2000.

                                    CABOT MICROELECTRONICS CORPORATION


                                    /s/ Matthew Neville
                                    ---------------------------------------
                                    By:  Matthew Neville
                                    President and Chief Executive Officer


                             POWER OF ATTORNEY

     KNOW ALL PERSONS BY THESE PRESENTS:

     That the undersigned officers and directors of Cabot  Microelectronics
Corporation,  a Delaware  corporation,  do hereby  constitute  and  appoint
Matthew  Neville  and  William C.  McCarthy,  and each of them,  the lawful
attorneys-in-fact  and agents with full power and  authority  to do any and
all acts and  things  and to  execute  any and all  instruments  which said
attorneys  and agents,  and any one of them,  determine may be necessary or
advisable  or  required  to enable  said  corporation  to  comply  with the
Securities  Act  and  any  rules  or  regulations  or  requirements  of the
Commission in connection with this Registration Statement. Without limiting
the  generality of the foregoing  power and  authority,  the powers granted
include  the  power  and  authority  to sign the  names of the  undersigned
officers  and  directors  in  the  capacities   indicated   below  to  this
Registration Statement,  to any and all amendments,  both pre-effective and
post-effective,  and supplements to this Registration Statement, and to any
and all  instruments or documents  filed as part of or in conjunction  with
this Registration  Statement or amendments or supplements thereof, and each
of the undersigned hereby ratifies and confirms that all said attorneys and
agents,  or any one of them, shall do or cause to be done by virtue hereof.
This Power of Attorney may be signed in several counterparts.


<PAGE>


     IN WITNESS WHEREOF, each of the undersigned has executed this Power of
Attorney as of the date indicated.

     Pursuant to the requirements of the Securities Act, this  Registration
Statement has been signed below by the following  persons in the capacities
and on the dates indicated.

      SIGNATURE                       TITLE                           DATE
----------------------  -----------------------------------  -------------------

/s/ Kennett F. Burnes         Chairman of the Board              April 7, 2000
----------------------
  Kennett F. Burnes


/s/ Matthew Neville           President and Chief Executive      April 7, 2000
----------------------        Officer, Director (Principal
   Matthew Neville            Executive Officer)


/s/ William C. McCarthy       Vice President, Chief Financial    April 7, 2000
----------------------        Officer and Treasurer (Principal
 William C. McCarthy          Financial and Accounting Officer)


/s/ Samuel W. Bodman          Director                           April 7, 2000
----------------------
   Samuel W. Bodman


/s/ William P. Noglows        Director                           April 7, 2000
----------------------
  William P. Noglows


<PAGE>


                             INDEX TO EXHIBITS

EXHIBIT NO.             DESCRIPTION OF EXHIBIT
-----------             ----------------------

4.1                     Form of Certificate of Incorporation of the Company
                        previously  filed as Exhibit  3.1 to the  Company's
                        Registration  Statement No.  333-95093 on Form S-1,
                        and incorporated herein by reference

4.2                     Form of By-Laws of the Company  previously filed as
                        Exhibit 3.2 to the Company's Registration Statement
                        No. 333-95093 on Form S-1, and incorporated  herein
                        by reference

4.3                     Form of Cabot Microelectronics Corporation Employee
                        Stock  Purchase Plan,  previously  filed as Exhibit
                        10.15 to the Company's  Registration  Statement No.
                        333-95093 on Form S-1, and  incorporated  herein by
                        reference

5.1*                    Opinion of Fried, Frank, Harris, Shriver & Jacobson

23.1                    Consent of Fried, Frank, Harris, Shriver & Jacobson
                        (included in Exhibit 5.1)

23.2*                   Consent of PricewaterhouseCoopers  LLP (independent
                        public accountants)


-------------------------
*    Filed herewith.
[{"type": "S-8", "sequence": "1", "secsgml_size_bytes": 19671}]
{"company-data": {"conformed-name": "CABOT MICROELECTRONICS CORP", "cik": "0001102934", "assigned-sic": "3290", "state-of-incorporation": "DE", "fiscal-year-end": "0930"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-34270", "film-number": "595823"}, "business-address": {"street1": "870 NORTH COMMONS DRIVE", "city": "AURORA", "state": "IL", "zip": "60504", "phone": "6303756631"}}
AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON APRIL 7, 2000
                                              REGISTRATION NO. 333-________
===========================================================================
                     SECURITIES AND EXCHANGE COMMISSION
                           WASHINGTON, D.C. 20549
                    -----------------------------------

                                  FORM S-8

                           REGISTRATION STATEMENT
                                   UNDER
                         THE SECURITIES ACT OF 1933

                    -----------------------------------
                     CABOT MICROELECTRONICS CORPORATION
           (Exact name of registrant as specified in its charter)

         DELAWARE                                           36-4324765
     (State or other                                     (I.R.S. Employer
     jurisdiction of                                  Identification Number)
     incorporation or
      organization)

                          870 NORTH COMMONS DRIVE
                           AURORA, ILLINOIS 60504
           (Address of registrant's principal executive offices)

      CABOT MICROELECTRONICS CORPORATION EMPLOYEE STOCK PURCHASE PLAN
                          (Full title of the plan)

                              MATTHEW NEVILLE
                   PRESIDENT AND CHIEF EXECUTIVE OFFICER
                     CABOT MICROELECTRONICS CORPORATION
                          870 NORTH COMMONS DRIVE
                           AURORA, ILLINOIS 60504
                               (630) 375-6631
         (Name, address, and telephone number of agent for service)

                      CALCULATION OF REGISTRATION FEE

==============================================================================
                                     PROPOSED      PROPOSED
                         AMOUNT TO    MAXIMUM       MAXIMUM
                            BE        OFFERING     AGGREGATE        AMOUNT OF
TITLE OF SECURITIES     REGISTERED   PRICE PER      OFFERING      REGISTRATION
 TO BE REGISTERED           (1)      SHARE (2)     PRICE (2)           FEE
------------------------------------------------------------------------------
Common Stock, par value   475,000    $25.25       $11,993,750.00    $3,167.00
$.001 per share (3)       shares
------------------------------------------------------------------------------

(1)  Plus such additional  number of shares as may be required in the event
     of a stock dividend,  stock split,  recapitalization  or other similar
     event in accordance  with Rule 416 of the  Securities  Act of 1933, as
     amended (the "Securities Act").

(2)  Estimated  solely for the purpose of determining the  registration fee
     pursuant to Rule 457(h) of the Securities Act.

(3)  Includes the Rights associated with the Common Stock.
PART I

                              EXPLANATORY NOTE

     This Form S-8  Registration  Statement  relates to  475,000  shares of
common  stock of Cabot  Microelectronics  Corporation,  par value $.001 per
share (the "Common  Stock"),  which may be issued under our Employee  Stock
Purchase Plan (the "ESPP").

     The  documents  containing  information  specified  by  Part I of this
Registration  Statement have been or will be sent or given to  participants
in the ESPP as specified in Rule  428(b)(1)  promulgated  by the Securities
and  Exchange  Commission  (the  "SEC")  under  the  Securities  Act.  Such
document(s) are not required to be filed with the SEC but constitute (along
with  the  documents  incorporated  by  reference  into  this  Registration
Statement pursuant to Item 3 of Part II hereof) a prospectus that meets the
requirements of Section 10(a) of the Securities Act.

     References  to  the  "Company"   shall  mean  Cabot   Microelectronics
Corporation, a Delaware corporation.

                                  PART II

             INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

     ITEM 3. INCORPORATION OF DOCUMENTS BY REFERENCE

     We file annual,  quarterly and special  reports,  proxy statements and
other  information with the SEC. You may read and copy any document we file
at the SEC's public  reference rooms in Washington,  D.C., New York, NY and
Chicago,  IL. Please call the SEC at 1-800-SEC-0330 for further information
on the public  reference  rooms.  Our SEC filings are also available to the
public from the SEC's web site at  http://www.sec.gov.  Reports,  proxy and
information  statements  and other  information  concerning  us can also be
inspected at the offices of the Nasdaq Stock Market's  National Market,  33
Whitehall Street, New York, NY 10004.

     The SEC allows us to "incorporate by reference"  information into this
Registration  Statement,   which  means  that  we  can  disclose  important
information to you by referring you to another  document  filed  separately
with the SEC. The information incorporated by reference is considered to be
part of this  Registration  Statement,  and later  information that we file
with the SEC will  automatically  update this  Registration  Statement.  We
incorporate  by reference  the following  documents and any future  filings
made  with  the  SEC  under  Sections  13(a),  13(c),  14 or  15(d)  of the
Securities  Exchange Act of 1934, as amended (the "Exchange Act"), prior to
the termination of the offering:

     (a)  Our  prospectus  filed with the SEC on April 4, 2000  pursuant to
          Rule 424(b) of the  Securities  Act in  connection  with the Form
          S-1,  which  includes our audited  financial  statements  for the
          fiscal year ended  September  30, 1999 and describes the terms of
          the Common Stock.

     (b)  Our  Registration  Statement  of Form 8-A  filed  with the SEC on
          April 3, 2000, which describes the terms of the Common Stock.

     ITEM 4. DESCRIPTION OF SECURITIES

     Not applicable.

     ITEM 5. INTERESTS OF NAMED EXPERTS AND COUNSEL

     Fried,  Frank,  Harris,  Shriver & Jacobson (a  partnership  including
professional corporations), New York, New York, will pass upon the validity
of the issuance of the shares of Common Stock.

     ITEM 6. INDEMNIFICATION OF DIRECTORS AND OFFICERS

     Section  145 of the  Delaware  General  Corporation  Law (the  "DGCL")
provides that a corporation may indemnify directors and officers as well as
other  employees and individuals  against  expenses  (including  attorneys'
fees),  judgments,  fines and amounts paid in settlement in connection with
specified  actions,   suits  and  proceedings,   whether  civil,  criminal,
administrative,  or investigative  (other than an action by or in the right
of the corporation -- a "derivative  action"),  if they acted in good faith
and in a manner  they  reasonably  believed  to be in or not opposed to the
best interests of the corporation  and, with respect to any criminal action
or  proceeding,  had no  reasonable  cause to  believe  their  conduct  was
unlawful.  A  similar  standard  is  applicable  in the case of  derivative
actions,  except that  indemnification  only extends to expenses (including
attorneys'  fees) incurred in connection  with the defense or settlement of
such action,  and the statute  requires court approval  before there can be
any indemnification where the person seeking indemnification has been found
liable to the corporation. The statute provides that it is not exclusive of
other indemnification that may be granted by a corporation's certificate of
incorporation,  bylaws,  disinterested  director  vote,  stockholder  vote,
agreement, or otherwise.

     Our  bylaws  and  our  certificate  of  incorporation  require  us  to
indemnify to the fullest  extent  authorized by the DGCL any person made or
threatened  to be made a party to an action,  suit or  proceeding,  whether
criminal,  civil,  administrative or  investigative,  by reason of the fact
that he or she is or was a director or officer of the Company, or is or was
serving at the request of the Company as a director,  officer,  employee or
agent of another corporation or of a partnership,  joint venture,  trust or
other enterprise.

     As permitted  by section  102(b)(7) of the DGCL,  our  certificate  of
incorporation  eliminates the liability of a director to the corporation or
its  stockholders for monetary damages for such breach of fiduciary duty as
a  director,  except  for  liabilities  arising  (a) from any breach of the
director's duty of loyalty to the corporation or its stockholders; (b) from
acts or omissions not in good faith or which involve intentional misconduct
or a knowing  violation of law; (c) under  section 174 of the DGCL;  or (d)
from any transaction from which the director  derived an improper  personal
benefit.

     We intend to obtain primary and excess insurance policies insuring our
directors  and  officers  and  those of our  subsidiaries  against  certain
liabilities  they may incur in their  capacity as directors  and  officers.
Under these policies,  the insurer, on our behalf, may also pay amounts for
which we have granted indemnification to the directors or officers.

     Additionally, reference is made to the Underwriting Agreement filed as
Exhibit 1.1 to our Registration  Statement No. 333-95093 on Form S-1, which
provides for  indemnification  by our  underwriters,  their  directors  and
officers who sign the  registration  statement  and persons who control us,
under certain circumstances.

     ITEM 7. EXEMPTION FROM REGISTRATION CLAIMED

     Not applicable.

     ITEM 8. EXHIBITS

EXHIBIT NO.             DESCRIPTION OF EXHIBIT
-----------             ----------------------

4.1                     Form of Certificate of Incorporation of the Company
                        previously  filed as Exhibit  3.1 to the  Company's
                        Registration  Statement No.  333-95093 on Form S-1,
                        and incorporated herein by reference

4.2                     Form of By-Laws of the Company  previously filed as
                        Exhibit 3.2 to the Company's Registration Statement
                        No. 333-95093 on Form S-1, and incorporated  herein
                        by reference

4.3                     Form of Cabot Microelectronics Corporation Employee
                        Stock  Purchase Plan,  previously  filed as Exhibit
                        10.15 to the Company's  Registration  Statement No.
                        333-95093 on Form S-1, and  incorporated  herein by
                        reference

5.1*                    Opinion of Fried, Frank, Harris, Shriver & Jacobson

23.1                    Consent of Fried, Frank, Harris, Shriver & Jacobson
                        (included in Exhibit 5.1)

23.2*                   Consent of PricewaterhouseCoopers  LLP (independent
                        public accountants)

-------------------------
*    Filed herewith.

     ITEM 9. UNDERTAKINGS

     The Company hereby undertakes:

          (a) To file, during any period in which offers or sales are being
     made, a post-effective amendment to this Registration Statement:

               (i) To include any prospectus  required by Section  10(a)(3)
          of the Securities Act;

               (ii) To  reflect  in the  prospectus  any  facts  or  events
          arising after the effective date of this  Registration  Statement
          (or the most  recent  post-effective  amendment  thereof)  which,
          individually or in the aggregate,  represent a fundamental change
          in the information set forth in this Registration Statement;

               (iii) To include any  material  information  with respect to
          the  plan  of  distribution  not  previously  disclosed  in  this
          Registration Statement or any material change to such information
          in this Registration Statement;

     provided,  however,  that  paragraphs (i) and (ii) do not apply if the
     information  required to be included in a post-effective  amendment by
     those  paragraphs  is  contained  in  periodic  reports  filed with or
     furnished to the SEC by the Company  pursuant to Section 13 or Section
     15(d) of the Exchange Act that are  incorporated  by reference in this
     Registration Statement.

          (b) That, for the purpose of determining  any liability under the
     Securities Act, each such post-effective  amendment shall be deemed to
     be a new  registration  statement  relating to the securities  offered
     therein,  and the  offering of such  securities  at that time shall be
     deemed to be the initial bona fide offering thereof.

          (c) To  remove  from  registration  by means of a  post-effective
     amendment any of the securities  being  registered which remain unsold
     at the termination of the offering.

          (d) That, for the purpose of determining  any liability under the
     Securities Act, each filing of the Company's annual report pursuant to
     Section   13(a)  or  Section   15(d)  of  the  Exchange  Act  that  is
     incorporated  by reference  in this  Registration  Statement  shall be
     deemed to be a new registration  statement  relating to the securities
     offered  therein,  and the  offering of such  securities  at that time
     shall be deemed to be the initial bona fide offering thereof.

     Insofar  as   indemnification   for  liabilities   arising  under  the
Securities  Act may be permitted  to  directors,  officers and  controlling
persons of the Company  pursuant to the  provisions  described in Item 6 of
this  Registration  Statement,  or otherwise,  the Company has been advised
that in the  opinion  of the SEC such  indemnification  is  against  public
policy as expressed in the Securities Act and is, therefore, unenforceable.
In the event  that a claim for  indemnification  against  such  liabilities
(other than the  payment by the  Company of expenses  incurred or paid by a
director,  officer or  controlling  person of the Company in the successful
defense of any action,  suit or  proceeding)  is asserted by such director,
officer or  controlling  person in  connection  with the  securities  being
registered,  the  Company  will,  unless in the  opinion of its counsel the
matter has been  settled  by  controlling  precedent,  submit to a court of
appropriate jurisdiction the question whether such indemnification by it is
against  public  policy  as  expressed  in the  Securities  Act and will be
governed by the final adjudication of such issue.
SIGNATURES

     Pursuant to the  requirements  of the  Securities  Act, the Registrant
certifies  that it has  reasonable  grounds to believe that it meets all of
the  requirements  for  filing  on  Form  S-8  and  has  duly  caused  this
Registration  Statement  to be  signed on its  behalf  by the  undersigned,
thereunto duly  authorized,  in the city of Aurora,  State of Illinois,  on
April 7, 2000.

                                    CABOT MICROELECTRONICS CORPORATION

                                    /s/ Matthew Neville
                                    ---------------------------------------
                                    By:  Matthew Neville
                                    President and Chief Executive Officer

                             POWER OF ATTORNEY

     KNOW ALL PERSONS BY THESE PRESENTS:

     That the undersigned officers and directors of Cabot  Microelectronics
Corporation,  a Delaware  corporation,  do hereby  constitute  and  appoint
Matthew  Neville  and  William C.  McCarthy,  and each of them,  the lawful
attorneys-in-fact  and agents with full power and  authority  to do any and
all acts and  things  and to  execute  any and all  instruments  which said
attorneys  and agents,  and any one of them,  determine may be necessary or
advisable  or  required  to enable  said  corporation  to  comply  with the
Securities  Act  and  any  rules  or  regulations  or  requirements  of the
Commission in connection with this Registration Statement. Without limiting
the  generality of the foregoing  power and  authority,  the powers granted
include  the  power  and  authority  to sign the  names of the  undersigned
officers  and  directors  in  the  capacities   indicated   below  to  this
Registration Statement,  to any and all amendments,  both pre-effective and
post-effective,  and supplements to this Registration Statement, and to any
and all  instruments or documents  filed as part of or in conjunction  with
this Registration  Statement or amendments or supplements thereof, and each
of the undersigned hereby ratifies and confirms that all said attorneys and
agents,  or any one of them, shall do or cause to be done by virtue hereof.
This Power of Attorney may be signed in several counterparts.
IN WITNESS WHEREOF, each of the undersigned has executed this Power of
Attorney as of the date indicated.

     Pursuant to the requirements of the Securities Act, this  Registration
Statement has been signed below by the following  persons in the capacities
and on the dates indicated.

      SIGNATURE                       TITLE                           DATE
----------------------  -----------------------------------  -------------------

/s/ Kennett F. Burnes         Chairman of the Board              April 7, 2000
----------------------
  Kennett F. Burnes

/s/ Matthew Neville           President and Chief Executive      April 7, 2000
----------------------        Officer, Director (Principal
   Matthew Neville            Executive Officer)

/s/ William C. McCarthy       Vice President, Chief Financial    April 7, 2000
----------------------        Officer and Treasurer (Principal
 William C. McCarthy          Financial and Accounting Officer)

/s/ Samuel W. Bodman          Director                           April 7, 2000
----------------------
   Samuel W. Bodman

/s/ William P. Noglows        Director                           April 7, 2000
----------------------
  William P. Noglows
INDEX TO EXHIBITS

EXHIBIT NO.             DESCRIPTION OF EXHIBIT
-----------             ----------------------

4.1                     Form of Certificate of Incorporation of the Company
                        previously  filed as Exhibit  3.1 to the  Company's
                        Registration  Statement No.  333-95093 on Form S-1,
                        and incorporated herein by reference

4.2                     Form of By-Laws of the Company  previously filed as
                        Exhibit 3.2 to the Company's Registration Statement
                        No. 333-95093 on Form S-1, and incorporated  herein
                        by reference

4.3                     Form of Cabot Microelectronics Corporation Employee
                        Stock  Purchase Plan,  previously  filed as Exhibit
                        10.15 to the Company's  Registration  Statement No.
                        333-95093 on Form S-1, and  incorporated  herein by
                        reference

5.1*                    Opinion of Fried, Frank, Harris, Shriver & Jacobson

23.1                    Consent of Fried, Frank, Harris, Shriver & Jacobson
                        (included in Exhibit 5.1)

23.2*                   Consent of PricewaterhouseCoopers  LLP (independent
                        public accountants)

-------------------------
*    Filed herewith.