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                                                                  EXHIBIT 24(a)


                             CERTIFIED RESOLUTION OF
                               BOARD OF DIRECTORS


         I, Nancy V. Van Allen, Senior Assistant Secretary of Merck & Co., Inc.,
a corporation duly organized and existing under the laws of the State of New
Jersey (the "Company"), do hereby certify that the following is a true copy of a
resolution adopted on July 24, 2001, at a meeting of the Directors of said
corporation held in the Town of Whitehouse Station, State of New Jersey, duly
called in accordance with the provisions of the By-Laws of said corporation, and
at which a quorum of Directors was present:

                  RESOLVED, that the Rosetta Inpharmatics, Inc. 1997 Stock Plan,
         Rosetta Inpharmatics, Inc. 2000 Stock Plan, and Rosetta Inpharmatics,
         Inc. 2000 Directors' Stock Option Plan (the "Plans") are hereby adopted
         in the form presented to this meeting with the following changes: (i)
         that the term "Company" used in such Plans shall mean Merck & Co.,
         Inc.; (ii) that such Plans be administered and amended by the
         Compensation and Benefits Committee of the Board of Directors of the
         Company with respect to persons subject to Section 16(b) of the
         Securities Exchange Act of 1934; (iii) that such Plans be administered
         and amended with respect to persons who are not subject to Section
         16(b) of the Securities Exchange Act of 1934 by the Chief Executive
         Officer of the Company; (iv) that the Chief Executive Officer of the
         Company may delegate such administration and right to amend to those
         persons that he or she deems appropriate; and (v) that no option or
         other awards may be granted under such Plans to any person on or after
         the date of the acquisition of Rosetta;

                  FURTHER RESOLVED, that the proper officers of the Company are
         hereby authorized and directed on behalf of the Company to prepare,
         execute and file with the Securities and Exchange Commission (the
         "SEC") a Registration Statement and any and all amendments thereto, and
         any and all exhibits and other documents relating thereto or required
         by law or regulation in connection therewith, for the registration
         under the Securities Act of 1933 of the shares of Common Stock of the
         Company which may be purchased under the Plans;

                  FURTHER RESOLVED, that Celia A. Colbert is hereby appointed
         and designated the person duly authorized to receive communications and
         notices from the SEC with respect to such Registration Statement or any
         amendments thereto and as agent for service of process;

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                  FURTHER RESOLVED, that each officer, director or employee of
         the Company who may be required to execute such Registration Statement
         or any amendments thereto (whether on behalf of the Company, or as an
         officer or director thereof, or by attesting the seal of the Company,
         or on behalf of the Plans, or otherwise), is hereby authorized to
         execute a power of attorney appointing Celia A. Colbert and Kenneth C.
         Frazier, and each of them severally, his or her true and lawful
         attorney or attorneys to execute in his or her name, place and stead
         (in any such capacity) such Registration Statement and any and all
         amendments thereto and any and all exhibits and other documents
         necessary or incidental in connection therewith, and to file the same
         with the SEC, each of said attorneys to have power to act with or
         without the other, and to have full power and authority to do and
         perform in the name and on behalf of each of said officers, directors
         and employees, or any of them, as the case may be, every act whatsoever
         necessary or advisable to be done in the premises as fully and to all
         intents and purposes as any such officer, director or employee might or
         could do in person;

                  FURTHER RESOLVED, that the proper officers of the Company are
         hereby authorized and directed to arrange with the New York Stock
         Exchange and the Philadelphia Stock Exchange for the listing of the
         additional shares of the Common Stock of the Company to be issued in
         connection with the Plans; and

                  FINALLY RESOLVED, that the proper officers of the Company,
         with the advice of counsel, are hereby authorized to take any action
         and to execute and deliver any letters, documents, agreements or other
         instruments as they deem necessary, appropriate or desirable to carry
         out the purposes and intents of this Special Resolution.




         IN WITNESS WHEREOF, I have hereunto subscribed my signature and affixed
the seal of the Corporation this 25th day of July, 2001.



                                          By:  /s/ Nancy V. Van Allen
                                               ---------------------------------
                                               Nancy V. Van Allen
                                               Senior Assistant Secretary



[Corporate Seal]



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