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

                                 January 6, 1998
                Date of Report (Date of earliest event reported)

                               OMNICOM GROUP INC.
             (Exact Name of Registrant as Specified in Its Charter)

                                    NEW YORK
                 (State or Other Jurisdiction of Incorporation)

               1-10551                                  13-1514814
       (Commission File Number)             (I.R.S. Employer Identification No.)

                               437 MADISON AVENUE
                            NEW YORK, NEW YORK 10022
                    (Address of Principal Executive Offices)

                                 (212) 415-3600
              (Registrant's Telephone Number, Including Area Code)


              ____________________________________________________
          (Former Name or Former Address, if Changed Since Last Report



Item 5.  Other Events.

     On January 6, 1998,  Omnicom Group Inc. (the "Company")  sold  $230,000,000
aggregate  principal  amount of 2 1/4% Convertible  Subordinated  Debentures due
2007  (the   "Debentures")   within  the  United   States  only  to   "Qualified
Institutional Buyers" (as defined in Rule 144A under the Securities Act of 1933,
as amended (the "Securities  Act")) in compliance with Rule 144A. Morgan Stanley
& Co.  Incorporated  acted as the placement  agent in the offering of Debentures
(the  "Offering").  The Debentures and the shares of the Company's common stock,
par value $0.50 per share (the "Common Stock"), into which the Debentures may be
converted were not registered under the Securities Act.

     The Debentures are convertible into Common Stock of the Company at any time
after 90 days  following the latest date of original  issuance  thereof  through
maturity,  unless previously  redeemed or repaid, at a conversion rate of 20.068
shares per bond (initially  representing a conversion price of $49.83),  subject
to adjustment in certain events.

Item 7.  Financial Statements, Pro Forma Financial Statements and Exhibits.

     1    Placement  Agreement  dated  December 4, 1997  between the Company and
          Morgan Stanley & Co. Incorporated

     4.1  Indenture  dated as of January 6, 1998  between  the  Company  and The
          Chase Manhattan Bank, as trustee

     4.2  Form of Debentures (included in Exhibit 4.1)

     4.3  Registration  Rights Agreement dated as of January 6, 1998 between the
          Company and Morgan Stanley & Co. Incorporated


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                                   SIGNATURES

Pursuant to 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.

                                        OMNICOM GROUP INC.

                                        By:    /s/  Barry J. Wagner
                                            ------------------------------------
                                            Barry J. Wagner, Secretary

Dated: January 20, 1998


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