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, 2004
                                                --------------------------------

                                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
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     (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, 2004 regarding
                                  earnings for second quarter 2004

     Exhibit 99.2                 Certain supplemental information not included
                                  in the press release


Item 9.   Regulation FD Disclosure; and
Item 12.  Results of Operations and Financial Condition.
--------------------------------------------------------

The following information is being furnished pursuant to both Item 9 and Item
12.

Incorporated by reference is a press release issued by the Registrant on July
21, 2004, regarding earnings for the second quarter 2004, 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 shall not be deemed to be "filed" for purposes of Section 18 of
the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or
otherwise subject to the liabilities of that Section, and is not incorporated by
reference in any filing under the Securities Act of 1933, as amended, or the
Exchange Act, except as expressly set forth by specific reference in such
filing.



                                   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, 2004                             By: /s/ Debra A. Bollwage
                                                     ---------------------------
                                                      DEBRA A. BOLLWAGE
                                                      Assistant Secretary





                                  EXHIBIT INDEX



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

 99.1    Press release issued July 21, 2004 regarding earnings for
         second quarter 2004

 99.2    Certain supplemental information not included in the press release