EXHIBIT 99.1

FOR IMMEDIATE RELEASE

Contact: Randall Weisenburger
         212-415-3393

         OMNICOM COMPLETES OFFERING OF $550 MILLION OF CONVERTIBLE DEBT

New York, New York. June 10, 2003. Omnicom Group Inc. (NYSE: OMC) announced that
it has  completed  the  sale  of $550  million  of  zero-coupon,  zero-accretion
convertible notes due 2033. The initial  purchasers will have a 13-day option to
purchase up to $50 million of additional notes.

The notes are  convertible  into 5.3 million  OMC common  shares  (assuming  the
additional  purchase  option is not  exercised)  if Omnicom  common shares reach
certain pricing thresholds,  initially $128.75 per share and increasing 5.0% per
quarter up to a maximum of $226.60 per share, or in certain other circumstances.

The $537.0 million of net proceeds of the  transaction  (assuming the additional
purchase  option is not  exercised) is expected to be used to repay a portion of
its  outstanding  indebtedness,  including its commercial  paper  borrowings and
amounts  outstanding  under its revolving  credit  facility as well as for other
general corporate purposes.

The notes are not  redeemable  by Omnicom  before 2010.  On June 15 2006,  2008,
2010,  2013,  2018, 2023 and each June 15 thereafter  through and including June
15,  2032,  noteholders  will  have the  option to  require  that  Omnicom  or a
financial  institution  designated by it  repurchase  the notes at the principal
amount at maturity.

This  release does not  constitute  an offer to sell or the  solicitation  of an
offer  to buy  securities.  The  notes  and  the  common  shares  issuable  upon
conversion have not been registered  under U.S. or state securities laws and may
not be offered or sold in the United States absent registration or an applicable
exemption from the registration requirements.

      Omnicom (www.omnicomgroup.com) is a leading global marketing and corporate
communications company.  Omnicom's branded networks and numerous specialty firms
provide advertising, strategic media planning and buying, direct and promotional
marketing,  public relations and other specialty communications services to over
5,000 clients in more than 100 countries.