Exhibit 8.1

                            [Letterhead of Jones Day]

                                February 13, 2004

Omnicom Group Inc.
437 Madison Avenue
New York, NY 10022

Ladies and Gentlemen:

      We have acted as special counsel for Omnicom Group Inc., a New York
corporation ("OGI"), Omnicom Capital Inc., a Connecticut corporation ("OCI") and
Omnicom Finance Inc., a Delaware corporation ("OFI" and together with OGI and
OCI, the "Issuers"), in connection with the Registration Statement on Form S-3
(the "Registration Statement") with the Securities and Exchange Commission
pursuant to the Securities Act of 1933, as amended (the "Act"). The Registration
Statement and the prospectus included therein relate to the registration for
resale of $892,273,000 aggregate principal amount of the Issuers' Zero Coupon
Zero Yield Convertible Notes due 2032 (the "Notes") and the shares of OGI's
Common Stock, par value $0.15 per share of OGI (the "Common Stock"), issuable
upon conversion of the Notes.

      In connection with our opinion we have reviewed and are relying upon the
Registration Statement, including the exhibits thereto, the representations
contained in a letter addressed to us from the Issuers and dated the date
hereof, and such other documents, records and instruments as we have deemed
necessary or appropriate for purposes of this opinion.

      This opinion is based upon current provisions of the Internal Revenue Code
of 1986, as amended, and the legislative history thereto and Treasury
Regulations issued thereunder, current administrative rulings and practices of
the Internal Revenue Service and judicial decisions, all of which are subject to
change or differing interpretation, possibly with retroactive effect, at any
time.

      Based upon and subject to the foregoing, we hereby confirm that the
opinion stated in the Registration Statement under the heading "Federal Income
Tax Considerations," subject to the qualifications set forth therein,
constitutes our opinion as to the treatment of the Notes for federal income tax
purposes. In addition, we are of the opinion that the discussion set forth in
the Registration Statement under the heading "Federal Income Tax
Considerations," subject to the qualifications set forth therein, to the extent
it describes federal income tax laws of the United States, constitutes a fair
and accurate summary in all material respects.

      We hereby consent to the filing of this opinion as Exhibit 8.1 to the
Registration Statement filed by the Issuers to register the resale of the Notes
and Common Stock under the Act and to the reference to us in the prospectus and
any prospectus supplements contained therein under the caption "Federal Income
Tax Considerations." In giving such consent, we do not hereby admit that we are
included in the category of persons whose consent is required under


Omnicom Group Inc.
February 13, 2004
Page 2


Section 7 of the Act or the rules and regulations of the Securities and Exchange
Commission promulgated thereunder.

                                      Very truly yours,

                                      /s/ Jones Day