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)    July 21, 2003
                                               ---------------------------------

                                MERCK & CO., Inc.
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             (Exact Name of Registrant as Specified in Its Charter)

                                   New Jersey
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                 (State or Other Jurisdiction of Incorporation)

            1-3305                                    22-1109110
-----------------------------------         ------------------------------------
  (Commission File Number)                  (I.R.S. Employer Identification No.)

         One Merck Drive, PO Box 100, Whitehouse Station, NJ 08889-0100
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           (Address of Principal Executive Offices)          (Zip Code)

        Registrant's Telephone Number, Including Area Code (908) 423-1000
                                                          ----------------------






Item 7. Financial Statements and Exhibits
-----------------------------------------

     (c)  Exhibits
          --------

     Exhibit 99.1 Press release issued July 21, 2003             Filed with
                  regarding earnings for second quarter 2003    this document

     Exhibit 99.2 Certain supplemental information               Filed with
                  not included in the press release             this document



Item 9. Regulation FD Disclosure
--------------------------------

Incorporated by reference is a press release issued by the Registrant on July
21, 2003, regarding earnings for the second quarter 2003, attached as Exhibit
99.1. Also incorporated by reference is certain supplemental information not
included in the press release, attached as Exhibit 99.2. This information is
being furnished pursuant to Item 12 - Results of Operations and Financial
Condition, of Form 8-K and is being presented under Item 9 of Form 8-K in
accordance with interim guidance issued by the Securities and Exchange
Commission in Release Nos. 33-8216 and 34-47583. This information is not deemed
to be "filed" for the purposes of Section 18 of the Securities Exchange Act of
1934 and is not incorporated by reference into any Securities Act registration
statements.



                                   SIGNATURES
                                   ----------

                  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.




                                                      MERCK & CO., Inc.




Date:  July 21, 2003                                  By: /s/ Debra A. Bollwage
                                                          ----------------------
                                                          DEBRA A. BOLLWAGE
                                                          Assistant Secretary








                                  EXHIBIT INDEX
                                  -------------


Exhibit
Number                     Description
-------                    -----------

 99.1                      Press release issued July 21, 2003
                           regarding earnings for second quarter 2003

 99.2                      Certain supplemental information not
                           included in the press release