Attached as Exhibit 100 to this Current Report on Form 8-K are the following documents from Omnicom Group Inc's. Quarterly Report on Form 10-Q for the quarter ended September 30, 2008, filed with the Securities and Exchange Commission on October 23, 2008, formatted in Extensible Business Reporting Language ("XBRL"): (i) the Condensed Consolidated Balance Sheets; (ii) the Condensed Consolidated Statements of Income; and, (iii) the Condensed Consolidated Statements of Cash Flows.

Users of this data are advised pursuant to Rule 401 of Regulation S-T that the financial and other information contained in the XBRL documents is unaudited and these documents are not the official publicly filed financial statements of Omnicom Group Inc. The purpose of submitting these XBRL formatted documents is to test the related format and technology and, as a result, investors should continue to rely on the official filed versions of all financial documents and not rely on the information in this Current Report on Form 8-K, including Exhibit 100, in making any investment decisions.

In accordance with Rule 402 of Regulation S-T, the information in this Current Report on Form 8-K, including Exhibit 100, shall not be deemed to be "filed" for purposes of Section 11 of the Securities Act of 1933, as amended, (the "Securities Act") or Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liability of those sections, and shall not be incorporated by reference into any registration statement or other document filed under the Securities Act or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.

(d) Exhibits.

Exhibit
 Number    Description
--------   -----------------------------------------------------------------------
100        The following materials from the Omnicom Group Inc. Quarterly Report on
           Form 10-Q for the quarter ended September 30, 2008, filed on October
           23, 2008 formatted in XBRL: (i) the Condensed Consolidated Balance
           Sheets; (ii) the Condensed Consolidated Statements of Income; and,
           (iii) the Condensed Consolidated Statements of Cash Flows.

           100. INS XBRL Instance Document

           100. SCH XBRL Taxonomy Extension Schema Document

           100. CAL XBRL Taxonomy Extension Calculation Linkbase Document

100. LAB XBRL Taxonomy Extension Label Linkbase Document

100. PRE XBRL Presentation Extension Linkbase Document

100. DEF XBRL Taxonomy Extension Definition Linkbase Document