<PAGE>   1
            AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON MAY 4, 1994

                                                            REGISTRATION NO. 33-

================================================================================
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                               ----------------
                                    FORM S-8
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
                               ----------------
                               MERCK & CO., INC.
               (Exact name of issuer as specified in its charter)

                                  P.O. Box 100
                                One Merck Drive
                      Whitehouse Station, New Jersey 08889
                                 (908) 423-1000
                    (Address of Principal Executive Offices)

<TABLE>
    <S>                                          <C>
           NEW JERSEY                                        22-1109110
    (State of Incorporation)                     (I.R.S. Employer Identification No.)
</TABLE>                                         

                     MEDICAL MARKETING GROUP, INC. ("MMG")
                        1991 CLASS B STOCK OPTION PLAN
                MMG 1991 SPECIAL NON-QUALIFIED STOCK OPTION PLAN
                             CERTAIN STOCK OPTIONS
                           (Full title of the plans)

                                CELIA A. COLBERT
                   SECRETARY AND ASSISTANT GENERAL COUNSEL
                               MERCK & CO., INC.
                                  P.O. BOX 100
                                ONE MERCK DRIVE
                      WHITEHOUSE STATION, NEW JERSEY 08889
                                 (908) 423-1000
           (Name, address and telephone number of agent for service)


                        CALCULATION OF REGISTRATION FEE


<TABLE>
<CAPTION>
                                                                   Proposed                        
                                                                   maximum        Proposed maximum                        
                                                                   offering          aggregate                            
                                                 Amount            price per          offering               Amount       
   Title of securities to be registered     to be registered        share*             price*          of registration fee
- ---------------------------------------------------------------------------------------------------------------------------
 <S>                                           <C>                 <C>              <C>                     <C>
 Common Stock (no par value)                   1,250,000           $ 29.69          $ 37,112,500            $ 12,804
                                               shares
===========================================================================================================================
</TABLE>

       * The prices stated above are estimated solely for the purpose of
determining the registration fee and are based on the average of the high and
low market prices of the stock as reported on the composite tape of New York
Stock Exchange listed issues on April 28, 1994

<PAGE>   2
                                    PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE

       The following documents filed by the registrant (Exchange Act File No.
1-3305) with the Securities and Exchange Commission are incorporated herein by
reference and made a part hereof:

       (1)    Annual Report on Form 10-K for the fiscal year ended December 31,
              1993;

       (2)    Proxy Statement for the Annual Meeting of Stockholders held
              April 26, 1994;

       (3)    The description of the Common Stock of the registrant set forth
              in the registrant's Registration Statement pursuant to Section
              12 of the Exchange Act, and any amendment or report filed for the
              purpose of updating any such description.

       All documents filed by the registrant pursuant to Section 13(a), 13(c),
14 or 15(d) of the Exchange Act from the date hereof and prior to the
termination of the offering of the securities offered hereby shall be deemed to
be incorporated by reference herein and to be a part hereof from the date of
filing of such documents.

ITEM 4.  DESCRIPTION OF SECURITIES

       Not applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL

       Not applicable.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

       The New Jersey Business Corporation Act provides that a New Jersey
corporation has the power to indemnify a director or officer against his or her
expenses and liabilities in connection with any proceeding involving the
director or officer by reason of his or her being or having been such a
director or officer, other than a proceeding by or in the right of the
corporation, if such a director or officer acted in good faith and in a manner
he or she reasonably believed to be in or not opposed to the best interests of
the corporation; and with respect to any criminal proceeding, such director or
officer had no reasonable cause to believe his or her conduct was unlawful.

       The indemnification and advancement of expenses shall not exclude any
other rights, including the right to be indemnified against liabilities and
expenses incurred in proceedings by or in the right of the corporation, to
which a director or officer may be entitled under a certificate of
incorporation, bylaw, agreement, vote of shareholders, or otherwise; provided
that no indemnification shall be made to or on behalf of a director or officer
if a judgment or other final adjudication adverse to the director or officer
establishes that his or her acts or omissions (a) were in breach of his or her
duty of loyalty to the corporation or its shareholders, (b) were not in good
faith or involved a knowing violation of law or (c) resulted in receipt by the
director or officer of an improper personal benefit.

       The Company's Restated Certificate of Incorporation provides that, to
the fullest extent permitted by the laws of the State of New Jersey, directors
and officers of the Corporation shall not be personally liable to the
Corporation or its stockholders for damages for breach of any duty owed to the
Corporation or its stockholders, except that a director or officer shall not be
relieved from liability for any breach of duty based upon an act or omission
(a) in breach of such person's duty of loyalty to the Corporation or its
stockholders, (b) not in good faith or involving a knowing violation of law or
(c) resulting in receipt by such person of an improper personal benefit.





                                      II-2
<PAGE>   3
       The By-Laws of the Company provide that a former, present or future
director, officer or employee of the Company or the legal representative of any
such director, officer or employee shall be indemnified by the Company:

              (a) against reasonable costs, disbursements and counsel fees paid
       or incurred where such person has been successful in the defense on the
       merits or otherwise of any pending, threatened or completed civil,
       criminal, administrative or arbitrative action, suit or proceeding,
       brought by reason of such person's being or having been such director,
       officer or employee, and

              (b) with respect to the defense of any such action, suit,
       proceeding, inquiry or investigation for which indemnification is not
       made under (a) above, against reasonable costs, disbursements (which
       shall include amounts paid in satisfaction of settlements, judgments,
       fines and penalties, exclusive, however, of any amount paid or payable
       to the Company) and counsel fees if such person acted in good faith and
       in a manner such person reasonably believed to be in or not opposed to
       the best interests of the Company, and in connection with any criminal
       proceedings such person also had no reasonable cause to believe the
       conduct was unlawful, with the determination as to whether the
       applicable standard of conduct was met to be made by a majority of the
       members of the Board of Directors (sitting as a Committee of the Board)
       who were not parties to such inquiry, investigation, action, suit or
       proceeding or by any one or more disinterested counsel to whom the
       question may be referred by the Board of Directors; provided, however,
       in connection with any proceeding by or in the right of the Company, no
       indemnification shall be provided as to any person adjudged by any court
       to be liable to the Company except as and to the extent determined by
       such court.

       The Company enters into indemnification agreements with its directors
and officers and enters into insurance agreements on its own behalf. The
indemnification agreements provide that the Company agrees to hold harmless and
indemnify its directors and officers to the fullest extent authorized or
permitted by the Business Corporation Act of the State of New Jersey, or any
other applicable law, or by any amendment thereof or other statutory provisions
authorizing or permitting such indemnification that is adopted after the date
hereof. Without limiting the generality of the foregoing, the Company agrees to
hold harmless and indemnify its directors and officers to the fullest extent
permitted by applicable law against any and all expenses, judgments, fines, and
amounts paid in settlement actually and reasonably incurred by its directors
and officers in connection with the defense of any present or future
threatened, pending, or completed claim, action, suit, or proceeding by reason
of the fact that they were, are, shall be, or shall have been a director or
officer of the Company, or are or were serving, shall serve, or shall have
served, at the request of the Company, as director or officer of another
corporation, partnership, joint venture, trust, employee benefit plan, or other
enterprise.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED

       Not applicable.

ITEM 8.  EXHIBITS

<TABLE>
<CAPTION>
Exhibit
Number                     Description                                           Method of Filing
- ------                     -----------                                           ----------------
 <S>    <C>                                                                      <C>
 4.1    Restated Certificate of Incorporation of the registrant (May 6, 1992)    Incorporated by reference to
                                                                                 Form 10-K Annual Report for
                                                                                 the fiscal year ended
                                                                                 December 31, 1992
</TABLE>





                                      II-3
<PAGE>   4
<TABLE>
<S>     <C>                                                                      
 4.2    By-Laws of the registrant (as amended November 22, 1988)                 Incorporated by
                                                                                 reference to Form     
                                                                                 10-K Annual Report    
                                                                                 for the fiscal year   
                                                                                 ended December 31,    
                                                                                 1988                  
 4.3    Medical Marketing Group, Inc. ("MMG") 1991 Class B Stock Option Plan              *
 4.4    Form of MMG Class B Non-Qualified Stock Option Agreement                          *
 4.5    MMG 1991 Special Non-Qualified Stock Option Plan                                  *
 4.6    Form of MMG 1991 Special Non-Qualified Stock Option Agreement                     *
 4.7    Stock Option Agreement dated as of July 15, 1991 between Micki Mikula             *
        and MMG
 4.8    Stock Option Agreement dated as of April 5, 1991 between Marianne                 *
        Vignone and MMG
 4.9    Stock Option Agreement dated as of April 5, 1991 between Peggy                    *
        Jablonski and MMG
4.10    Stock Option Agreement dated as of April 22, 1991 between Roger                   *
        Holstein and MMG
4.11    Stock Option Agreement dated as of May 1, 1992 between Carl Kanter and            *
        MMG
4.12    Assumption Agreement dated April 6, 1994 between registrant and MMG               *
 5      Opinion of Bert I. Weinstein, Associate General Counsel of the                    *
        registrant
23      Consent of Arthur Andersen & Co.                                                  *
24      Power of Attorney of Board of Directors                                  Included at Page II-6 of this
                                                                                 Registration Statement
- ---------------                                                                                        
</TABLE>

* Filed with this Registration Statement.

ITEM 9. UNDERTAKINGS

     The undersigned registrant hereby undertakes:

          1.  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 of 1933;

               (ii)  To reflect in the prospectus any facts or events arising
          after the effective date of the 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 the registration statement;

               (iii)  To include any material information with respect to the
          plan of distribution not previously disclosed in the registration
          statement or any material change to such information in the
          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





                                      II-4
<PAGE>   5
contained in periodic reports filed by the registrant pursuant to section 13 or
section 15(d) of the Securities Exchange Act of 1934 that are incorporated by
reference in the registration statement.

     2.  That, for the purpose of determining any liability under the
Securities Act of 1933, 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.

     3.  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.

     4.  That, for purposes of determining any liability under the Securities
Act of 1933, each filing of the registrant's annual report pursuant to Section
13(a) or 15(d) of the Securities Exchange Act of 1934 (and, where applicable,
each filing of an employee benefit plan's annual report pursuant to Section
15(d) of the Securities Exchange Act of 1934) that is incorporated by reference
in the 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.

     5.  Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the registrant pursuant to the foregoing provisions, or otherwise,
the registrant has been advised that in the opinion of the Securities and
Exchange Commission such indemnification is against public policy as expressed
in the Act and is, therefore, unenforceable. In the event that a claim for
indemnification against such liabilities (other than the payment by the
registrant of expenses incurred or paid by a director, officer or controlling
person of the registrant 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 registrant 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 Act and
will be governed by the final adjudication of such issue.





                                      II-5
<PAGE>   6
                                   SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, as amended,
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 Whitehouse Station, State of New Jersey, on the 29th day
of April, 1994.

                                             MERCK & CO., INC.
                                             
                                             
                                             
                                             By: /s/ P. Roy Vagelos, M.D.
                                                --------------------------
                                                     P. Roy Vagelos, M.D.
                                             (Chairman of the Board, President
                                             and Chief Executive Officer)

                               POWER OF ATTORNEY

         Each person whose signature appears below constitutes and appoints
Celia A. Colbert or Mary M. McDonald, and each of them, as his or her true and
lawful attorney-in-fact and agent, with full power of substitution and
resubstitution, for him or her and in his or her name, place and stead, in any
and all capacities, to sign any and all amendments (including post-effective
amendments) to this Registration Statement and all documents relating thereto,
and to file the same, with all exhibits thereto, and other documents in
connection therewith, with the Securities and Exchange Commission granting unto
said attorneys-in-fact and agents, and each of them, full power and authority
to do and perform each and every act and thing necessary or advisable to be
done in and about the premises, as fully to all intents and purposes as he or
she might or could do in person, hereby ratifying and confirming all that said
attorneys-in-fact and agents, or any of them, or their substitute or
substitutes, may lawfully do or cause to be done by virtue hereof.

         Pursuant to the requirements of the Securities Act of 1933, as
amended, this Registration Statement has been signed by the following persons
in the capacities and on the dates indicated.

<TABLE>
<CAPTION>
SIGNATURE                                        TITLE                                          DATE
- ---------                                        -----                                          ----
    <S>                                    <C>                                            <C>
/s/ P. Roy Vagelos, M.D.                   Chairman of the Board,                         April 29, 1994
- --------------------------                 President and Chief Executive                                
    P. Roy Vagelos, M.D.                   Officer (Principal Executive 
                                           Officer) and Director        
                                                                        
                                           

/s/ Judy C. Lewent                         Senior Vice President and                      April 29, 1994
- ---------------------------                Chief Financial Officer                                      
    Judy C. Lewent                         (Principal Financial Officer)
                                                                        
                                           
/s/ Peter E. Nugent                        Vice President, Controller                     April 29, 1994
- ---------------------------                (Principal Accounting Officer)                               
    Peter E. Nugent                                                      
                                           
/s/ H. Brewster Atwater, Jr.               Director                                       April 29, 1994
- ----------------------------                                                                            
    H. Brewster Atwater, Jr.

/s/ Sir Derek Birkin                       Director                                       April 29, 1994
- ----------------------------                                                                            
    Sir Derek Birkin
    
/s/ Lawrence A. Bossidy                    Director                                       April 29, 1994
- -----------------------------                                                                           
    Lawrence A. Bossidy
    
/s/ William G. Bowen, Ph.D.                Director                                       April 29, 1994
- -----------------------------                                                                           
    William G. Bowen, Ph.D.
</TABLE>





                                      II-6
<PAGE>   7
<TABLE>
<CAPTION>
SIGNATURE                                        TITLE                                          DATE
- ---------                                        -----                                          ----
    <S>                                    <C>                                            <C>
/s/ Carolyne K. Davis, Ph.D.               Director                                       April 29, 1994
- ----------------------------                                                                            
    Carolyne K. Davis, Ph.D.

/s/ Lloyd C. Elam, M.D.                    Director                                       April 29, 1994
- ----------------------------                                                                            
    Lloyd C. Elam, M.D.

/s/ Charles E. Exley, Jr.                  Director                                       April 29, 1994
- ----------------------------                                                                            
    Charles E. Exley, Jr.

/s/ William N. Kelley, M.D.                Director                                       April 29, 1994
- ----------------------------                                                                            
    William N. Kelley, M.D.

/s/ Ruben F. Mettler, Ph.D.                Director                                       April 29, 1994
- ----------------------------                                                                            
    Ruben F. Mettler, Ph.D.

/s/ Richard S. Ross, M.D.                  Director                                       April 29, 1994
- -----------------------------                                                                           
    Richard S. Ross, M.D.

/s/ Dennis Weatherstone                    Director                                       April 29, 1994
- -----------------------------                                                                           
    Dennis Weatherstone

/s/ Martin J. Wygod                        Director                                       April 29, 1994
- -----------------------------                                                                           
    Martin J. Wygod
</TABLE>





                                      II-7
<PAGE>   8
Exhibit
Number              Description                          Method of Filing

 4.1   Restated Certificate of Incorporation of the      Incorporated by
       registrant (May 6, 1992)                          reference to Form   
                                                         10-K Annual Report  
                                                         for the fiscal year 
                                                         ended December 31,  
                                                         1992
                                                         
4.2    By-Laws of the registrant (as amended             Incorporated by
       November 22, 1988)                                reference to Form   
                                                         10-K Annual Report  
                                                         for the fiscal year 
                                                         ended December 31,  
                                                         1988

4.3    Medical Marketing Group, Inc. ("MMG") 1991 Class B         *
       Stock Option Plan                                 
                                                                         
4.4    Form of MMG Class B Non-Qualified Stock Option             *
       Agreement

4.5    MMG 1991 Special Non-Qualified Stock Option Plan           *

4.6    Form of MMG 1991 Special Non-Qualified Stock               *
       Option Agreement

4.7    Stock Option Agreement dated as of July 15, 1991           *
       between Micki Mikula and MMG

4.8    Stock Option Agreement dated as of April 5, 1991           *
       between Marianne Vignone and MMG

4.9    Stock Option Agreement dated as of April 5, 1991           *
       between Peggy Jablonski and MMG

4.10   Stock Option Agreement dated as of April 22, 1991          *
       between Roger Holstein and MMG

4.11   Stock Option Agreement dated as of May 1, 1992             *
       between Carl Kanter and MMG

4.12   Assumption Agreement dated April 6, 1994 between           *
       registrant and MMG

5      Opinion of Bert I. Weinstein, Associate General            *
       Counsel of the registrant

23     Consent of Arthur Andersen & Co.                           *

24     Power of Attorney of Board of Directors           Included at Page II-
                                                         6 of this
                                                         Registration
                                                         Statement

* Filed with this Registration Statement.
[{"type": "S-8", "sequence": "1", "description": "MERCK & CO., INC. FORM S-8", "secsgml_size_bytes": 27171}]
{"company-data": {"conformed-name": "MERCK & CO INC", "cik": "0000064978", "assigned-sic": "2834", "irs-number": "221109110", "state-of-incorporation": "NJ", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "033-53463", "film-number": "94525977"}, "business-address": {"street1": "ONE MERCK DR", "street2": "P O BOX 100", "city": "WHITEHOUSE STATION", "state": "NJ", "zip": "08889-0100", "phone": "9084231000"}, "mail-address": {"street1": "ONE MERCK DR", "street2": "PO BOX 100 WS3AB-05", "city": "WHITEHOUSE STATION", "state": "NJ", "zip": "08889-0100"}}
1
            AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON MAY 4, 1994

                                                            REGISTRATION NO. 33-

================================================================================
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                               ----------------
                                    FORM S-8
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
                               ----------------
                               MERCK & CO., INC.
               (Exact name of issuer as specified in its charter)

                                  P.O. Box 100
                                One Merck Drive
                      Whitehouse Station, New Jersey 08889
                                 (908) 423-1000
                    (Address of Principal Executive Offices)
NEW JERSEY                                        22-1109110
    (State of Incorporation)                     (I.R.S. Employer Identification No.)
MEDICAL MARKETING GROUP, INC. ("MMG")
                        1991 CLASS B STOCK OPTION PLAN
                MMG 1991 SPECIAL NON-QUALIFIED STOCK OPTION PLAN
                             CERTAIN STOCK OPTIONS
                           (Full title of the plans)

                                CELIA A. COLBERT
                   SECRETARY AND ASSISTANT GENERAL COUNSEL
                               MERCK & CO., INC.
                                  P.O. BOX 100
                                ONE MERCK DRIVE
                      WHITEHOUSE STATION, NEW JERSEY 08889
                                 (908) 423-1000
           (Name, address and telephone number of agent for service)

                        CALCULATION OF REGISTRATION FEE
Proposed                        
                                                                   maximum        Proposed maximum                        
                                                                   offering          aggregate                            
                                                 Amount            price per          offering               Amount       
   Title of securities to be registered     to be registered        share*             price*          of registration fee
- ---------------------------------------------------------------------------------------------------------------------------
Common Stock (no par value)                   1,250,000           $ 29.69          $ 37,112,500            $ 12,804
                                               shares
===========================================================================================================================
* The prices stated above are estimated solely for the purpose of
determining the registration fee and are based on the average of the high and
low market prices of the stock as reported on the composite tape of New York
Stock Exchange listed issues on April 28, 1994
2
                                    PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE

       The following documents filed by the registrant (Exchange Act File No.
1-3305) with the Securities and Exchange Commission are incorporated herein by
reference and made a part hereof:

       (1)    Annual Report on Form 10-K for the fiscal year ended December 31,
              1993;

       (2)    Proxy Statement for the Annual Meeting of Stockholders held
              April 26, 1994;

       (3)    The description of the Common Stock of the registrant set forth
              in the registrant's Registration Statement pursuant to Section
              12 of the Exchange Act, and any amendment or report filed for the
              purpose of updating any such description.

       All documents filed by the registrant pursuant to Section 13(a), 13(c),
14 or 15(d) of the Exchange Act from the date hereof and prior to the
termination of the offering of the securities offered hereby shall be deemed to
be incorporated by reference herein and to be a part hereof from the date of
filing of such documents.

ITEM 4.  DESCRIPTION OF SECURITIES

       Not applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL

       Not applicable.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

       The New Jersey Business Corporation Act provides that a New Jersey
corporation has the power to indemnify a director or officer against his or her
expenses and liabilities in connection with any proceeding involving the
director or officer by reason of his or her being or having been such a
director or officer, other than a proceeding by or in the right of the
corporation, if such a director or officer acted in good faith and in a manner
he or she reasonably believed to be in or not opposed to the best interests of
the corporation; and with respect to any criminal proceeding, such director or
officer had no reasonable cause to believe his or her conduct was unlawful.

       The indemnification and advancement of expenses shall not exclude any
other rights, including the right to be indemnified against liabilities and
expenses incurred in proceedings by or in the right of the corporation, to
which a director or officer may be entitled under a certificate of
incorporation, bylaw, agreement, vote of shareholders, or otherwise; provided
that no indemnification shall be made to or on behalf of a director or officer
if a judgment or other final adjudication adverse to the director or officer
establishes that his or her acts or omissions (a) were in breach of his or her
duty of loyalty to the corporation or its shareholders, (b) were not in good
faith or involved a knowing violation of law or (c) resulted in receipt by the
director or officer of an improper personal benefit.

       The Company's Restated Certificate of Incorporation provides that, to
the fullest extent permitted by the laws of the State of New Jersey, directors
and officers of the Corporation shall not be personally liable to the
Corporation or its stockholders for damages for breach of any duty owed to the
Corporation or its stockholders, except that a director or officer shall not be
relieved from liability for any breach of duty based upon an act or omission
(a) in breach of such person's duty of loyalty to the Corporation or its
stockholders, (b) not in good faith or involving a knowing violation of law or
(c) resulting in receipt by such person of an improper personal benefit.

                                      II-2
3
       The By-Laws of the Company provide that a former, present or future
director, officer or employee of the Company or the legal representative of any
such director, officer or employee shall be indemnified by the Company:

              (a) against reasonable costs, disbursements and counsel fees paid
       or incurred where such person has been successful in the defense on the
       merits or otherwise of any pending, threatened or completed civil,
       criminal, administrative or arbitrative action, suit or proceeding,
       brought by reason of such person's being or having been such director,
       officer or employee, and

              (b) with respect to the defense of any such action, suit,
       proceeding, inquiry or investigation for which indemnification is not
       made under (a) above, against reasonable costs, disbursements (which
       shall include amounts paid in satisfaction of settlements, judgments,
       fines and penalties, exclusive, however, of any amount paid or payable
       to the Company) and counsel fees if such person acted in good faith and
       in a manner such person reasonably believed to be in or not opposed to
       the best interests of the Company, and in connection with any criminal
       proceedings such person also had no reasonable cause to believe the
       conduct was unlawful, with the determination as to whether the
       applicable standard of conduct was met to be made by a majority of the
       members of the Board of Directors (sitting as a Committee of the Board)
       who were not parties to such inquiry, investigation, action, suit or
       proceeding or by any one or more disinterested counsel to whom the
       question may be referred by the Board of Directors; provided, however,
       in connection with any proceeding by or in the right of the Company, no
       indemnification shall be provided as to any person adjudged by any court
       to be liable to the Company except as and to the extent determined by
       such court.

       The Company enters into indemnification agreements with its directors
and officers and enters into insurance agreements on its own behalf. The
indemnification agreements provide that the Company agrees to hold harmless and
indemnify its directors and officers to the fullest extent authorized or
permitted by the Business Corporation Act of the State of New Jersey, or any
other applicable law, or by any amendment thereof or other statutory provisions
authorizing or permitting such indemnification that is adopted after the date
hereof. Without limiting the generality of the foregoing, the Company agrees to
hold harmless and indemnify its directors and officers to the fullest extent
permitted by applicable law against any and all expenses, judgments, fines, and
amounts paid in settlement actually and reasonably incurred by its directors
and officers in connection with the defense of any present or future
threatened, pending, or completed claim, action, suit, or proceeding by reason
of the fact that they were, are, shall be, or shall have been a director or
officer of the Company, or are or were serving, shall serve, or shall have
served, at the request of the Company, as director or officer of another
corporation, partnership, joint venture, trust, employee benefit plan, or other
enterprise.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED

       Not applicable.

ITEM 8.  EXHIBITS
Exhibit
Number                     Description                                           Method of Filing
- ------                     -----------                                           ----------------
4.1    Restated Certificate of Incorporation of the registrant (May 6, 1992)    Incorporated by reference to
                                                                                 Form 10-K Annual Report for
                                                                                 the fiscal year ended
                                                                                 December 31, 1992
II-3
4
4.2    By-Laws of the registrant (as amended November 22, 1988)                 Incorporated by
                                                                                 reference to Form     
                                                                                 10-K Annual Report    
                                                                                 for the fiscal year   
                                                                                 ended December 31,    
                                                                                 1988                  
 4.3    Medical Marketing Group, Inc. ("MMG") 1991 Class B Stock Option Plan              *
 4.4    Form of MMG Class B Non-Qualified Stock Option Agreement                          *
 4.5    MMG 1991 Special Non-Qualified Stock Option Plan                                  *
 4.6    Form of MMG 1991 Special Non-Qualified Stock Option Agreement                     *
 4.7    Stock Option Agreement dated as of July 15, 1991 between Micki Mikula             *
        and MMG
 4.8    Stock Option Agreement dated as of April 5, 1991 between Marianne                 *
        Vignone and MMG
 4.9    Stock Option Agreement dated as of April 5, 1991 between Peggy                    *
        Jablonski and MMG
4.10    Stock Option Agreement dated as of April 22, 1991 between Roger                   *
        Holstein and MMG
4.11    Stock Option Agreement dated as of May 1, 1992 between Carl Kanter and            *
        MMG
4.12    Assumption Agreement dated April 6, 1994 between registrant and MMG               *
 5      Opinion of Bert I. Weinstein, Associate General Counsel of the                    *
        registrant
23      Consent of Arthur Andersen & Co.                                                  *
24      Power of Attorney of Board of Directors                                  Included at Page II-6 of this
                                                                                 Registration Statement
- ---------------
* Filed with this Registration Statement.

ITEM 9. UNDERTAKINGS

     The undersigned registrant hereby undertakes:

          1.  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 of 1933;

               (ii)  To reflect in the prospectus any facts or events arising
          after the effective date of the 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 the registration statement;

               (iii)  To include any material information with respect to the
          plan of distribution not previously disclosed in the registration
          statement or any material change to such information in the
          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

                                      II-4
5
contained in periodic reports filed by the registrant pursuant to section 13 or
section 15(d) of the Securities Exchange Act of 1934 that are incorporated by
reference in the registration statement.

     2.  That, for the purpose of determining any liability under the
Securities Act of 1933, 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.

     3.  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.

     4.  That, for purposes of determining any liability under the Securities
Act of 1933, each filing of the registrant's annual report pursuant to Section
13(a) or 15(d) of the Securities Exchange Act of 1934 (and, where applicable,
each filing of an employee benefit plan's annual report pursuant to Section
15(d) of the Securities Exchange Act of 1934) that is incorporated by reference
in the 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.

     5.  Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the registrant pursuant to the foregoing provisions, or otherwise,
the registrant has been advised that in the opinion of the Securities and
Exchange Commission such indemnification is against public policy as expressed
in the Act and is, therefore, unenforceable. In the event that a claim for
indemnification against such liabilities (other than the payment by the
registrant of expenses incurred or paid by a director, officer or controlling
person of the registrant 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 registrant 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 Act and
will be governed by the final adjudication of such issue.

                                      II-5
6
                                   SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, as amended,
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 Whitehouse Station, State of New Jersey, on the 29th day
of April, 1994.

                                             MERCK & CO., INC.
                                             
                                             
                                             
                                             By: /s/ P. Roy Vagelos, M.D.
                                                --------------------------
                                                     P. Roy Vagelos, M.D.
                                             (Chairman of the Board, President
                                             and Chief Executive Officer)

                               POWER OF ATTORNEY

         Each person whose signature appears below constitutes and appoints
Celia A. Colbert or Mary M. McDonald, and each of them, as his or her true and
lawful attorney-in-fact and agent, with full power of substitution and
resubstitution, for him or her and in his or her name, place and stead, in any
and all capacities, to sign any and all amendments (including post-effective
amendments) to this Registration Statement and all documents relating thereto,
and to file the same, with all exhibits thereto, and other documents in
connection therewith, with the Securities and Exchange Commission granting unto
said attorneys-in-fact and agents, and each of them, full power and authority
to do and perform each and every act and thing necessary or advisable to be
done in and about the premises, as fully to all intents and purposes as he or
she might or could do in person, hereby ratifying and confirming all that said
attorneys-in-fact and agents, or any of them, or their substitute or
substitutes, may lawfully do or cause to be done by virtue hereof.

         Pursuant to the requirements of the Securities Act of 1933, as
amended, this Registration Statement has been signed by the following persons
in the capacities and on the dates indicated.
SIGNATURE                                        TITLE                                          DATE
- ---------                                        -----                                          ----
/s/ P. Roy Vagelos, M.D.                   Chairman of the Board,                         April 29, 1994
- --------------------------                 President and Chief Executive                                
    P. Roy Vagelos, M.D.                   Officer (Principal Executive 
                                           Officer) and Director        
                                                                        
                                           

/s/ Judy C. Lewent                         Senior Vice President and                      April 29, 1994
- ---------------------------                Chief Financial Officer                                      
    Judy C. Lewent                         (Principal Financial Officer)
                                                                        
                                           
/s/ Peter E. Nugent                        Vice President, Controller                     April 29, 1994
- ---------------------------                (Principal Accounting Officer)                               
    Peter E. Nugent                                                      
                                           
/s/ H. Brewster Atwater, Jr.               Director                                       April 29, 1994
- ----------------------------                                                                            
    H. Brewster Atwater, Jr.

/s/ Sir Derek Birkin                       Director                                       April 29, 1994
- ----------------------------                                                                            
    Sir Derek Birkin
    
/s/ Lawrence A. Bossidy                    Director                                       April 29, 1994
- -----------------------------                                                                           
    Lawrence A. Bossidy
    
/s/ William G. Bowen, Ph.D.                Director                                       April 29, 1994
- -----------------------------                                                                           
    William G. Bowen, Ph.D.
II-6
7
SIGNATURE                                        TITLE                                          DATE
- ---------                                        -----                                          ----
/s/ Carolyne K. Davis, Ph.D.               Director                                       April 29, 1994
- ----------------------------                                                                            
    Carolyne K. Davis, Ph.D.

/s/ Lloyd C. Elam, M.D.                    Director                                       April 29, 1994
- ----------------------------                                                                            
    Lloyd C. Elam, M.D.

/s/ Charles E. Exley, Jr.                  Director                                       April 29, 1994
- ----------------------------                                                                            
    Charles E. Exley, Jr.

/s/ William N. Kelley, M.D.                Director                                       April 29, 1994
- ----------------------------                                                                            
    William N. Kelley, M.D.

/s/ Ruben F. Mettler, Ph.D.                Director                                       April 29, 1994
- ----------------------------                                                                            
    Ruben F. Mettler, Ph.D.

/s/ Richard S. Ross, M.D.                  Director                                       April 29, 1994
- -----------------------------                                                                           
    Richard S. Ross, M.D.

/s/ Dennis Weatherstone                    Director                                       April 29, 1994
- -----------------------------                                                                           
    Dennis Weatherstone

/s/ Martin J. Wygod                        Director                                       April 29, 1994
- -----------------------------                                                                           
    Martin J. Wygod
II-7
8
Exhibit
Number              Description                          Method of Filing

 4.1   Restated Certificate of Incorporation of the      Incorporated by
       registrant (May 6, 1992)                          reference to Form   
                                                         10-K Annual Report  
                                                         for the fiscal year 
                                                         ended December 31,  
                                                         1992
                                                         
4.2    By-Laws of the registrant (as amended             Incorporated by
       November 22, 1988)                                reference to Form   
                                                         10-K Annual Report  
                                                         for the fiscal year 
                                                         ended December 31,  
                                                         1988

4.3    Medical Marketing Group, Inc. ("MMG") 1991 Class B         *
       Stock Option Plan                                 
                                                                         
4.4    Form of MMG Class B Non-Qualified Stock Option             *
       Agreement

4.5    MMG 1991 Special Non-Qualified Stock Option Plan           *

4.6    Form of MMG 1991 Special Non-Qualified Stock               *
       Option Agreement

4.7    Stock Option Agreement dated as of July 15, 1991           *
       between Micki Mikula and MMG

4.8    Stock Option Agreement dated as of April 5, 1991           *
       between Marianne Vignone and MMG

4.9    Stock Option Agreement dated as of April 5, 1991           *
       between Peggy Jablonski and MMG

4.10   Stock Option Agreement dated as of April 22, 1991          *
       between Roger Holstein and MMG

4.11   Stock Option Agreement dated as of May 1, 1992             *
       between Carl Kanter and MMG

4.12   Assumption Agreement dated April 6, 1994 between           *
       registrant and MMG

5      Opinion of Bert I. Weinstein, Associate General            *
       Counsel of the registrant

23     Consent of Arthur Andersen & Co.                           *

24     Power of Attorney of Board of Directors           Included at Page II-
                                                         6 of this
                                                         Registration
                                                         Statement

* Filed with this Registration Statement.