Exhibit 32.1

           CHIEF EXECUTIVE OFFICER CERTIFICATION PURSUANT TO 18 U.S.C.
                SECTION 1350, AS ADOPTED PURSUANT TO SECTION 906
                        OF THE SARBANES-OXLEY ACT OF 2002

      The certification set forth below is hereby made solely for the purpose of
satisfying the requirements of Section 906 of the Sarbanes-Oxley Act of 2002 and
may not be relied upon or used for any other purposes.

      In connection with the Quarterly Report of Waters Corporation (the
"Company") on Form 10-Q for the period ended April 2, 2005, as filed with the
Securities and Exchange Commission on the date hereof (the "Report"), I, Douglas
A. Berthiaume, Chief Executive Officer of the Company, certify, pursuant to 18
U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley
Act of 2002, that to my knowledge: (1) the Report fully complies with the
requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934;
and (2) the information contained in the Report fairly presents, in all material
respects, the financial condition and results of operations of the Company.

      A signed original of this written statement required by Section 906 or
other document authenticating, acknowledging or otherwise adopting the signature
that appears in typed form within the electronic version of this written
statement required by Section 906 has been provided to the Company and will be
retained by the Company and furnished to the Securities and Exchange Commission
or its staff upon request.

Date: May 6, 2005

                                                 By: /s/ Douglas A. Berthiaume
                                                     ---------------------------
                                                     Douglas A. Berthiaume
                                                     Chief Executive Officer