PROSPECTUS SUPPLEMENT
(To Prospectus Dated June 3, 2002)
                                                Filed Pursuant to Rule 424(b)(3)
                                            Registration Statement No. 333-86194

                                  $900,000,000

                               OMNICOM GROUP INC.
                Zero Coupon Zero Yield Convertible Notes due 2032

      This  prospectus   supplement   relates  to  the  resale  by  the  selling
securityholders  of Zero Coupon Zero Yield Convertible Notes due 2032 of Omnicom
Group Inc. and the shares of common stock  issuable upon the  conversion  and/or
redemption of the notes.

      This  prospectus  supplement  should  be  read  in  conjunction  with  the
prospectus  dated June 3, 2002,  which is to be delivered  with this  prospectus
supplement.  All  capitalized  terms  used  but not  defined  in the  prospectus
supplement shall have the meanings given to them in the prospectus.

      The  following  information  replaces  in  its  entirety  the  information
provided in the prospectus under the caption "Selling Securityholders."

                             SELLING SECURITYHOLDERS

      The notes were originally  issued by us and sold to J.P. Morgan Securities
Inc.,  Goldman  Sachs & Co. and  Salomon  Smith  Barney  Inc.,  to whom we refer
elsewhere  as  the  "initial  purchasers,"  in a  transaction  exempt  from  the
registration requirements of the federal securities laws. The initial purchasers
resold  the  notes  to  persons  reasonably  believed  by them to be  "qualified
institutional  buyers" as defined by Rule 144A  under the  Securities  Act.  The
selling securityholders, which term includes their transferees, pledgees, donees
or successors, may from time to time offer and sell pursuant to this prospectus,
as  amended or  supplemented,  any and all of the notes and the shares of common
stock issuable upon conversion and/or redemption of the notes.

      Set  forth  below  are the  names  of  each  selling  securityholder,  the
principal  amount of notes that may be offered  by such  selling  securityholder
pursuant  to this  prospectus,  as  amended or  supplemented,  and the number of
shares of common stock into which such notes are convertible, each to the extent
known to us as of the date of this prospectus.  Unless set forth below,  none of
the selling  securityholders  has had a material  relationship with us or any of
our predecessors or affiliates within the past three years.

      The following  table sets forth certain  information  received by us on or
prior to June 25, 2002. However,  any or all of the notes or common stock listed
below may be  offered  for sale  pursuant  to this  prospectus,  as  amended  or
supplemented,  by the selling securityholders from time to time. Accordingly, no
estimate  can be given as to the  amounts of notes or common  stock that will be
held by the selling  securityholders  upon  consummation  of any such sales.  In
addition,   the  selling   securityholders   identified  below  may  have  sold,
transferred  or otherwise  disposed of all or a portion of their notes since the
date  on  which  the  information   regarding  their  notes  was  provided,   in
transactions exempt from the registration requirements of the Securities Act.






                                                       Aggregate
                                                       Principal
                                                       Amount of
                                                        Notes at     Percentage of  Common Stock   Common Stock
                                                      Maturity that      Notes       Owned Prior    Registered
                       Name                            may be Sold    Outstanding   to Conversion    Hereby(1)
-------------------------------------------------     -------------   ------------  -------------  -------------
                                                                                                
AIG DKR SoundShore Holdings Ltd. ................    $  9,200,000          1.0%            --            83,628
AIG DKR SoundShore Opportunity Holding
   Fund Ltd. ....................................       6,120,000            *             --            55,630
AIG DKR SoundShore Strategic Holding
   Fund Ltd. ....................................       4,680,000            *             --            42,541
Alpha U.S. Sub Fund VIII, LLC ...................       2,000,000            *             --            18,180
Alta Partners Holdings, LDC .....................      30,000,000          3.3             --           272,700
American Pioneer Life Insurance Company of
   New York .....................................          80,000            *             --               727
American Progressive Life and Health Insurance
   Company of New York ..........................          80,000            *             --               727
American Public Entity Excess Pool ..............          80,000            *             --               727
Amerisure Mutual Insurance Company ..............         400,000            *             --             3,636
Argent Classic Convertible Arbitrage Fund L.P. ..       2,925,000            *             --            26,588
Argent Classic Convertible Arbitrage
   Fund (Bermuda) Ltd. ..........................       5,000,000            *             --            45,450
Argent LowLev Convertible Arbitrage Fund LLC ....         500,000            *             --             4,545
Argent LowLev Convertible Arbitrage Fund Ltd. ...       7,580,000            *             --            68,902
Aristeia International Limited ..................      28,875,000          3.2             --           262,473
Aristeia Trading LLC ............................       8,625,000            *             --            78,401
B.G.I. Global Investors c/o Forest Investment
   Mngt L.L.C. ..................................         167,000            *             --             1,518
BMO Nesbitt Burns Inc. ..........................       8,000,000            *             --            72,720
Canyon Capital Arbitrage Master Fund, Ltd. ......      12,000,000          1.3             --           109.080
Canyon MAC 18 (PMF) .............................       2,800,000            *             --            25,452
Canyon Value Realization Fund (Cayman), Ltd. ....      16,400,000          1.8             --           149,076
Canyon Value Realization Fund, L.P. .............       8,800,000            *             --            79,992
CDC IXIS Paris ..................................      10,000,000          1.1            400            90,900
Celina Mutual Insurance Company .................          20,000            *             --               181
Central States Health and Life Company of
   Omaha ........................................         210,000            *             --             1,908
CFFX, LLC .......................................       3,000,000            *             --            27,270
Continental Assurance Company on Behalf of its
  Separate Account (E) ..........................       3,800,000            *             --            34,542
Continental Casualty Company ....................      13,700,000          1.5              *           124,533
Credit Suisse First Boston Europe Ltd. ..........      19,400,000          2.2             --           176,346
CSA Fraternal Life Insurance Company ............         120,000            *             --             1,090
Dakota Truck Underwriters .......................          20,000            *             --               181
Deephaven Domestic Convertible Trading Ltd. .....      78,000,000          8.7             --           709,020
Deutsche Bank Securities Inc. ...................      15,600,000          1.7             --           141,804
Forest Alternative Strategies, II ...............         133,000            *             --             1,208
Forest Fulerum Fund L.L.P. ......................       2,667,000            *             --            24,243
Forest Global Convertible Fund Series A-5 .......       1,700,000            *             --            15,453
Gaia Offshore Master Fund Ltd. ..................      11,700,000          1.3             --           106,353
Global Bermuda Limited Partnership ..............      14,000,000          1.6             --           127,260
HBK Master Fund L.P. ............................       5,000,000            *             --            45,450
HFR CA Select Fund ..............................         600,000            *             --             5,454
Innovest Finanzdienstleistungs AG ...............         545,000            *             --             4,954
JMG Convertible Investments, LP .................      10,000,000          1.1             --            90,900
JMG Triton Offshore Fund, Ltd. ..................      20,000,000          2.2             --           181,800
JP Morgan Securities Inc. .......................      78,540,000          8.7             --           713,928
KBC Financial Products USA Inc. .................       5,750,000            *             --            52,267
Lakeshore International, Ltd. ...................      56,000,000          6.2             --           509,040
Lincoln Heritage Life Insurance Company .........          40,000            *             --               363
LLT Limited .....................................         600,000            *             --             5,454
Lyxor Master Fund c/o Forest Investment
   Mngt L.L.C. ..................................       9,333,000          1.0             --            84,836
Lyxor Master Fund ...............................       1,800,000            *             --            16,362
Lyxor Master Fund Ref: Argent/LowLev CB .........       1,000,000            *             --             9,090
Main Street America Assurance Company ...........         400,000            *             --             3,636
Marquette Indemnity and Life Insurance
   Company ......................................          80,000            *             --               727
Merrill Lynch International Limited(2) ..........      40,000,000          4.4             --           363,600
Michigan Mutual Insurance Co. ...................         900,000            *             --             8,181
Michigan Professional Insurance Exchange ........          60,000            *             --               545
Midwest Security Life ...........................         240,000            *             --             2,181
MLQA Convertible Securities Arbitrage, Ltd. .....       5,000,000            *             --            45,450
Morgan Stanley & Co. ............................      70,000,000          7.8             --           636,300
Mutual Protective Insurance Company .............         900,000            *             --             8,181
National Mutual Insurance Company ...............          30,000            *             --               272
NCMIC ...........................................         470,000            *             --             4,272
New Era Life Insurance Company ..................          50,000            *             --               454
Nicholas Applegate Investment Grade Convertible .          15,000            *             --               136
Oak Casualty Insurance Company ..................          40,000            *             --               363
Onyx Fund Holdings, LDC .........................      18,000,000          2.0             --           163,620
Oklahoma Attorneys Mutual Insurance Company .....          10,000            *             --                90
Phico Insurance Company .........................         550,000            *             --             4,999
Physicians Mutual Insurance Company .............         550,000            *             --             4,999
Physicians Life Insurance Company ...............         250,000            *             --             2,272
Pioneer Insurance Company .......................          80,000            *             --               727
Premera Blue Cross ..............................       1,150,000            *             --            10,453
R(2) Investments, LDC ...........................      55,000,000          6.1             --           499,950
RBC Capital Services Inc. c/o Forest Investment
   Mngt L.L.C. ..................................         133,000            *             --             1,208
Relay 11 Holdings c/o  Forest Investment
   Mngt  L.L.C. .................................       3,000,000            *             --            27,270
Royal Bank of Canada ............................      10,000,000          1.1             --            90,900
Sagamore Hill Hub Fund Ltd. .....................      37,500,000          4.2             --           340,875
Salomon Brothers Asset Management, Inc. .........      20,000,000          2.2             --           181,800
Salomon Smith Barney Inc. .......................      27,645,000          3.1             --           251,293
San Diego County Employees
   Retirement Association .......................       1,900,000            *             --            17,271
Scor Life RE Convertible ........................         120,000            *             --             1,090
Sylvan (IMA) Ltd. c/o Forest Investment
   Mngt L.L.C. ..................................       2,000,000            *             --            18,180
Standard Mutual Insurance Company ...............         220,000            *             --             1,999
State National Insurance Company ................          90,000            *             --               818
Texas Hospital Insurance Exchange ...............          20,000            *             --               181
Transguard Insurance Company of America, Inc. ...         750,000            *             --             6,817
Tribeca Investments L.L.C. ......................      18,000,000          2.0             --           163,620
Tuscarora Wayne Mutual Insurance Company ........          20,000            *             --               181
UBS O'Connor LLC F/B/O UBS Global Equity
   Arbitrage Master Ltd. ........................      26,750,000          3.0             --           243,157
UBS O'Connor LLC F/B/O O'Connor Global
   Convertible Portfolio ........................       1,750,000            *             --            15,907
United National Insurance Company ...............         200,000            *             --             1,818
VESTA-WEX Insurance Exchange IASA ...............         150,000            *             --             1,363
Western Home Insurance Company ..................         170,000            *             --             1,545
Westward Life Insurance Company .................         150,000            *             --             1,363
West Virginia Fire Insurance Company ............          10,000            *             --                90
Wisconsin Lawyers Mutual Insurance Company ......         190,000            *             --             1,727
Wisconsin Mutual Insurance Company ..............         100,000            *             --               909
World Insurance Company .........................         400,000            *             --             3,636
Zazove Convertible Arbitrage Fund L.P. ..........         800,000            *             --             7,272
Zazove Hedged Convertible Fund L.P. .............       2,900,000            *             --            26,361
Zazove Income Fund ..............................       2,000,000            *             --            18,180
Zurich Master Hedge Fund c/o Forest
   Investment Mngt L.L.C. .......................         267,000            *             --             2,427
Zurich Institutional Benchmark Master
   Fund Ltd. c/o Argent .........................         500,000            *             --             4,545
Zurich Institutional Benchmarks Master
   Fund Ltd. ....................................       2,800,000            *             --            25,452
All other holders of notes or future transferees,
   pledges, donees or successors of any such
   holders(2)(3) ................................      28,100,000          3.1             --           255,429
                                                     ------------       ------           ----         ---------
   Total(4) .....................................    $900,000,000       100.00%           400         8,181,000
                                                     ============       ======           ====         =========


*  Less than 1%

----------
(1)   Assumes conversion of all of the holder's notes at a conversion rate of
      9.09 shares of common stock per $1,000 principal amount at maturity of the
      notes. However, this conversion rate will be subject to adjustment as
      described under "Description of the Notes -- Conversion Rights." As a
      result, the amount of common stock issuable upon conversion of the notes
      may increase or decrease in the future.

(2)   Merrill Lynch, Pierce Fenner & Smith Incorporated has advised us that it
      is not aware of any position, office or directorship relationship with
      Omnicom or its affiliates. However, Merrill Lynch has advised us that it
      may have from time to time acted in a financial investment advisory
      capacity to Omnicom.

(3)   Information  about  other  selling  securityholders  will be set  forth in
      prospectus supplements, if required.

(4)   Assumes  that any other  holders  of  notes,  or any  future  transferees,
      pledgees, donees or successors of or from any such other holders of notes,
      do not  beneficially  own any common  stock  other  than the common  stock
      issuable upon conversion of the notes at the initial conversion rate.

(5)   Amounts may not sum due to rounding.

      The preceding table has been prepared based upon information  furnished to
us by the  selling  securityholders  named  in the  table.  From  time to  time,
additional information concerning ownership of the notes and common stock may be
known by certain holders thereof not named in the preceding table,  with whom we
believe we have no affiliation.  Information  about the selling  securityholders
may  change  over  time.  Any  changed  information  will be set forth in future
prospectus supplements.

                                   ----------

            The date of this Prospectus Supplement is June 26, 2002.