FORM 10-Q

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                   Quarterly Report Under Section 13 or 15(d)
                     of the Securities Exchange Act of 1934

For Quarter Ended:  June 30, 1998

Commission file number:  1-10551

                               Omnicom Group Inc.
             (Exact name of registrant as specified in its charter)

            New York                                  13-1514814          
(State or other jurisdiction of                      (IRS Employer
 incorporation or organization)                   Identification No.)

 437 Madison Avenue, New York, New York                 10022  
(Address of principal executive offices)              (Zip Code)

                                 (212) 415-3600
              (Registrant's telephone number, including area code)

Indicate by check mark whether the registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the  preceding 12 months (or for such  shorter  period that the  registrant  was
required  to file  such  reports),  and  (2) has  been  subject  to such  filing
requirements for the past 90 days. Yes _X_ No __

The number of shares of common stock of the Company  issued and  outstanding  at
July 31, 1998 is 169,718,100.



                       OMNICOM GROUP INC. AND SUBSIDIARIES
                                      INDEX

                                                                        Page No.
                                                                        --------

PART I. FINANCIAL INFORMATION

      Item 1.   Financial Statements:                                 
                                                                      
                Consolidated Condensed Balance Sheets -               
                   June 30, 1998, December 31, 1997 and               
                   June 30, 1997                                           2
                                                                      
                Consolidated Condensed Statements of Income -         
                   Three Months and Six Months                        
                   Ended June 30, 1998 and 1997                            3
                                                                      
                Consolidated Condensed Statements of Cash Flows -     
                   Six Months Ended June 30, 1998 and 1997                 4
                                                                      
                Notes to Consolidated Condensed Financial             
                   Statements                                              5-11
                                                                      
      Item 2.   Management's Discussion of Financial Condition        
                   and Results of Operations                               12-19
                                                                      
PART II. OTHER INFORMATION                                     
                                                                      
      Item 4.   Submission of Matters to a Vote                       
                   of Security Holders                                     20-21
                                                                      
      Item 6.   Exhibits                                                   21

                                      -1-
                                                                  


                          PART I. FINANCIAL INFORMATION
                          Item 1. Financial Statements
                       OMNICOM GROUP INC. AND SUBSIDIARIES
                     CONSOLIDATED CONDENSED BALANCE SHEETS
                             (Dollars in Thousands)



                            Assets                         June 30,     December 31,    June 30,
                            ------                           1998          1997           1997
                                                             ----          ----           ----
                                                                                      
Current assets:
     Cash and cash equivalents                           $   337,918    $   556,436    $   294,028
     Investments available-for-sale, at market, which
       approximates cost                                      36,620         87,668         95,471
     Accounts receivable, less allowance for doubtful
       accounts of $38,703, $32,190 and $26,232            2,354,889      1,908,532      1,685,742
     Billable production orders in process                   298,160        183,145        200,731
     Prepaid expenses and other current assets               423,551        252,617        238,882
                                                         -----------    -----------    -----------
         Total current assets                              3,451,138      2,988,398      2,514,854

Furniture, equipment and leasehold improvements at
  cost, less accumulated depreciation and amortization
  of $364,452, $336,926 and $317,156                         306,677        239,667        228,883
Investments in affiliates                                    287,947        281,264        236,615
Intangibles, less amortization of $256,924, $235,257
  and $214,605                                             1,849,704      1,234,539      1,148,131
Deferred tax benefits                                         81,519         68,086         73,410
Deferred charges and other assets                            173,589        153,789        139,598
                                                         -----------    -----------    -----------
        Total assets                                     $ 6,150,574    $ 4,965,743    $ 4,341,491
                                                         ===========    ===========    ===========
       Liabilities and Shareholders' Equity
       ------------------------------------

Current liabilities:
     Accounts payable                                    $ 2,647,842    $ 2,595,255    $ 1,903,841
     Payable to banks                                         96,795         17,672         28,640
     Other accrued liabilities                             1,122,562        885,569        729,713
     Accrued taxes on income                                  63,061         80,489         77,333
                                                         -----------    -----------    -----------
        Total current liabilities                          3,930,260      3,578,985      2,739,527
Long term debt                                               837,924        341,665        545,014
Deferred compensation and other liabilities                  232,186        114,668        143,461
Minority interests                                            71,469         63,686         71,964

Shareholders' equity:
     Common stock                                             88,624         86,918         86,834
     Additional paid-in capital                              637,302        533,412        525,693
     Retained earnings                                       647,758        555,038        478,861
     Unamortized restricted stock                            (71,306)       (46,745)       (56,104)
     Cumulative translation adjustment                       (40,830)       (47,947)       (34,558)
     Treasury stock                                         (182,813)      (213,937)      (159,201)
                                                         -----------    -----------    -----------
        Total shareholders' equity                         1,078,735        866,739        841,525
                                                         -----------    -----------    -----------
        Total liabilities and shareholders' equity       $ 6,150,574    $ 4,965,743    $ 4,341,491
                                                         ===========    ===========    ===========


  The accompanying notes to consolidated condensed financial statements are an
                     integral part of these balance sheets.


                                       -2-


                       OMNICOM GROUP INC. AND SUBSIDIARIES
                   CONSOLIDATED CONDENSED STATEMENTS OF INCOME
                  (Dollars in Thousands, Except Per Share Data)


                                       Three Months Ended June 30,  Six Months Ended June 30,
                                       ---------------------------  -------------------------
                                           1998          1997         1998           1997
                                           ----          ----         ----           ----
                                                                              
Revenues:
   Commissions and fees                $ 1,051,510    $ 786,341    $ 1,912,486    $ 1,482,918

Operating expenses:
   Salaries and related costs              600,469      444,200      1,121,635        865,685
   Office and general expenses             276,224      219,267        516,865        420,369
                                       -----------    ---------    -----------    -----------
            Total operating expenses       876,693      663,467      1,638,500      1,286,054
                                       -----------    ---------    -----------    -----------
Operating profit                           174,817      122,874        273,986        196,864
Net interest expense:
   Interest and dividend income             (8,156)      (6,273)       (14,118)        (9,257)
   Interest paid or accrued                 18,742       11,234         32,216         18,567
                                       -----------    ---------    -----------    -----------
            Net interest expense            10,586        4,961         18,098          9,310
                                       -----------    ---------    -----------    -----------
Income before income taxes                 164,231      117,913        255,888        187,554

Income taxes:
   Federal                                  28,985       17,491         44,330         28,940
   State and local                           6,084        5,771         12,442         10,462
   International                            34,691       24,783         50,991         36,909
                                       -----------    ---------    -----------    -----------
            Total income taxes              69,760       48,045        107,763         76,311
                                       -----------    ---------    -----------    -----------
Income after income taxes                   94,471       69,868        148,125        111,243
Equity in affiliates                         5,278        7,282         10,258         11,426
Minority interests                         (13,757)     (10,751)       (21,488)       (16,202)
                                       -----------    ---------    -----------    -----------
            Net income                 $    85,992    $  66,399    $   136,895    $   106,467
                                       ===========    =========    ===========    ===========
Earnings per share:
- -------------------
   Net income:
           Basic                       $      0.51    $    0.41    $      0.83    $      0.67
           Diluted                     $      0.50    $    0.40    $      0.81    $      0.66

Dividends declared per common share    $     0.125    $    0.10    $      0.25    $      0.20



  The accompanying notes to consolidated condensed financial statements are an
                       integral part of these statements.


                                       -3-



                 OMNICOM GROUP INC. AND SUBSIDIARIES
            CONSOLIDATED CONDENSED STATEMENTS OF CASH FLOWS
                       (Dollars in Thousands)



                                                                  Six Months Ended
                                                                      June 30,
                                                                ---------------------
                                                                   1998         1997
                                                                ----------    -------
                                                                             
Cash flows from operating activities:
     Net income                                                 $ 136,895    $ 106,467
     Adjustments to reconcile net income to net cash
       used for operating activities:

     Depreciation and amortization of tangible assets              33,479       28,111
     Amortization of intangible assets                             24,772       18,781
     Minority interests                                            21,488       16,202
     Earnings of affiliates in excess of dividends received        (4,451)      (6,523)
     Decrease in deferred tax benefits                              3,957        9,776
     Provision for losses on accounts receivable                    3,907        3,160
     Amortization of restricted shares                              9,968        8,525
     Increase in accounts receivable                             (142,213)    (130,993)
     Increase in billable production                              (98,184)     (46,033)
     Increase in other current assets                             (85,912)     (33,198)
     Decrease in accounts payable                                (181,011)    (148,406)
     Decrease in other accrued liabilities                        (61,955)     (44,103)
     (Decrease) increase in accrued income taxes                  (24,095)       8,867
     Other                                                        (14,934)     (26,634)
                                                                ---------    ---------
         Net cash used for operating activities                  (378,289)    (236,001)
                                                                ---------    ---------

Cash flows from investing activities:
     Capital expenditures                                         (52,905)     (31,502)
     Payments for purchases of equity interests in
       subsidiaries and affiliates, net of cash acquired         (336,775)    (181,271)
     Proceeds from sales of equity interests in
       subsidiaries and affiliates                                  1,206          320
     Payments for purchases of investments available-for-sale
       and other investments                                      (42,819)     (84,931)
     Proceeds from sales of investments available-for-sale
       and other investments                                       93,611        6,849
                                                                ---------    ---------
         Net cash used for investing activities                  (337,682)    (290,535)
                                                                ---------    ---------

Cash flows from financing activities:
     Net (repayments) borrowings under lines of credit             (6,348)      10,283
     Share transactions under employee stock plans                 29,060       20,971
     Proceeds from issuance of shares                             171,035         --
     Proceeds from issuance of principal of debt obligations      551,841      359,269
     Repayment of principal of debt obligations                  (126,735)     (12,939)
     Dividends and loans to minority stockholders                 (18,665)      (6,389)
     Dividends paid                                               (40,738)     (31,743)
     Purchase of treasury shares                                  (71,921)     (11,043)
                                                                ---------    ---------
         Net cash provided by financing activities                487,529      328,409
                                                                ---------    ---------

Effect of exchange rate changes on cash and cash equivalents        9,924      (18,112)
                                                                ---------    ---------
     Net decrease in cash and cash equivalents                   (218,518)    (216,239)
Cash and cash equivalents at beginning of period                  556,436      510,267
                                                                ---------    ---------
Cash and cash equivalents at end of period                      $ 337,918    $ 294,028
                                                                =========    =========
Supplemental Disclosures:
     Income taxes paid                                          $ 127,330    $  59,109
                                                                =========    =========
     Interest paid                                              $  28,435    $   8,662
                                                                =========    =========


  The accompanying notes to consolidated condensed financial statements are an
                       integral part of these statements.


                                      -4-


                       OMNICOM GROUP INC. AND SUBSIDIARIES
              NOTES TO CONSOLIDATED CONDENSED FINANCIAL STATEMENTS

- --------------------------------------------------------------------------------

1)          The consolidated  condensed  interim financial  statements  included
      herein have been prepared by the Company,  without audit,  pursuant to the
      rules and regulations of the Securities and Exchange  Commission.  Certain
      information  and  footnote  disclosures  normally  included  in  financial
      statements  prepared in  accordance  with  generally  accepted  accounting
      principles  have been  condensed  or  omitted  pursuant  to such rules and
      regulations.

2)          These  statements  reflect  all  adjustments,  consisting  of normal
      recurring accruals which, in the opinion of management,  are necessary for
      a  fair  presentation  of  the  information  contained  therein.   Certain
      reclassifications  have been made to the June 30, 1997 reported amounts to
      conform them with the June 30, 1998 and  December  31, 1997  presentation.
      Also, all amounts  presented  give effect to a two-for-one  stock split in
      the form of a 100%  stock  dividend  completed  in  December  1997.  These
      consolidated  condensed financial statements should be read in conjunction
      with the consolidated  financial  statements and notes thereto included in
      the Company's  annual report on Form 10-K for the year ended  December 31,
      1997.

3)          Results  of  operations  for  interim  periods  are not  necessarily
      indicative of annual results.


                                      -5-


                       OMNICOM GROUP INC. AND SUBSIDIARIES
         NOTES TO CONSOLIDATED CONDENSED FINANCIAL STATEMENTS(CONTINUED)

- --------------------------------------------------------------------------------

4)          Basic  earnings per share is based upon the weighted  average number
      of common shares outstanding during the period. Diluted earnings per share
      is based on such average number of common shares outstanding, common share
      equivalents  outstanding,  and if  dilutive,  is adjusted  for the assumed
      conversion of the Company's  convertible  subordinated  debentures and the
      assumed  increase  in net income for the after tax  interest  cost of such
      debentures.   At  June  30,  1998,  the  2.25%  Convertible   Subordinated
      Debentures  had been  outstanding  since  January  6,  1998 and the  4.25%
      Convertible  Subordinated  Debentures had been  outstanding for the entire
      six  months.  At  June  30,  1997,  the  4.25%  Convertible   Subordinated
      Debentures  had been  outstanding  since  January 3,  1997.  The number of
      shares used in the  computations  of basic and diluted  earnings per share
      were as follows:

                        Three Months                        Six Months
                        Ended June 30,                    Ended June 30,
                        --------------                    --------------
                    1998             1997              1998            1997
                    ----             ----              ----            ----
Basic EPS        167,156,400      160,268,100      165,177,600      159,635,700
Diluted EPS      182,294,000      170,205,600      175,643,000      162,527,900

            For  purposes of  computing  diluted  earnings per share for the six
      months ended June 30, 1998, the 2.25% Convertible  Subordinated Debentures
      were not reflected in the computation,  as their inclusion would have been
      anti-dilutive.


                                      -6-


                       OMNICOM GROUP INC. AND SUBSIDIARIES
         NOTES TO CONSOLIDATED CONDENSED FINANCIAL STATEMENTS(CONTINUED)

- --------------------------------------------------------------------------------

            For  purposes of  computing  diluted  earnings per share for the six
      months ended June 30, 1997, the 4.25% Convertible  Subordinated Debentures
      were not reflected in the computation,  as their inclusion would have been
      anti-dilutive.

5)          The Company has adopted the  provisions  of  Statement  of Financial
      Accounting  Standards No. 130,  "Reporting  Comprehensive  Income",  which
      requires  presentation  of  information  on  comprehensive  income and its
      components in financial statements.  In the Company's case,  comprehensive
      income includes net income and foreign currency  translation  adjustments.
      Total comprehensive income and its components were as follows:

                                     Three Months              Six Months
                                    Ended June 30,           Ended June 30,
                                  -----------------        ------------------
                                     (Dollars in              (Dollars in
                                      Thousands)               Thousands)
                                  1998         1997        1998          1997
                                  ----         ----        ----          ----

Net Income                      $85,992       $66,399    $136,895      $106,467

Foreign Currency
  Translation Adjustments         8,722       (12,227)      7,395       (38,048)
                                -------       -------    --------      --------
Total Comprehensive Income      $94,714       $54,172    $144,290      $ 68,419
                                =======       =======    ========      ========
 
6)          In June  1998,  the  Financial  Accounting  Standards  Board  issued
      Statement  of Financial  Accounting  Standards  No. 133 ("SFAS No.  133"),
      "Accounting for Derivative  Instruments and Hedging Activities".  SFAS No.
      133 establishes accounting and reporting standards requiring


                                      -7-


                       OMNICOM GROUP INC. AND SUBSIDIARIES
         NOTES TO CONSOLIDATED CONDENSED FINANCIAL STATEMENTS(CONTINUED)

- --------------------------------------------------------------------------------

      that every derivative instrument (including certain derivative instruments
      embedded in other contracts) be recorded in the balance sheet as either an
      asset or liability  measured at its fair value. SFAS No. 133 requires that
      changes in the derivative's fair value be recognized currently in earnings
      unless specific hedge accounting  criteria are met. Special accounting for
      qualifying hedges allows a derivative's gains and losses to offset related
      results on the hedged item in the income  statement,  and requires  that a
      company must formally document, designate, and assess the effectiveness of
      transactions that receive hedge accounting.

            SFAS No. 133 is effective for fiscal years  beginning after June 15,
      1999. A company may also implement SFAS No. 133 as of the beginning of any
      fiscal quarter after issuance (that is, fiscal quarters beginning June 16,
      1998 and thereafter).  SFAS No. 133 cannot be applied retroactively.  Once
      implemented,  SFAS No. 133 must be applied to (a)  derivative  instruments
      and (b) certain derivative  instruments  embedded in hybrid contracts that
      were issued,  acquired, or substantively  modified after December 31, 1997
      (and, at a company's election, before January 1, 1998).


                                      -8-


                       OMNICOM GROUP INC. AND SUBSIDIARIES
         NOTES TO CONSOLIDATED CONDENSED FINANCIAL STATEMENTS(CONTINUED)

- --------------------------------------------------------------------------------

            The Company intends to adopt SFAS No. 133 for its fiscal year ending
      December 31, 2000.  The adoption of the  provisions  of SFAS No. 133 would
      not have had a material effect on the Company's  results of operations for
      the  quarter  or six  months  ending  June  30,  1998 or on its  financial
      position as of that date.

7)          In  January  1998,  the  Company   completed  the   acquisitions  of
      Fleishman-Hillard, Inc., GPC International Holdings Inc. and Palmer Jarvis
      Inc.  These  acquisitions  have been  accounted  for under the  pooling of
      interests  method of  accounting.  The  number  of shares  issued or to be
      issued by the Company in connection with these  acquisitions is 3,550,366.
      The assets, liabilities, shareholders' equity and results of operations of
      the companies  acquired are not, either  individually or in the aggregate,
      material to the Company and, therefore, the Company's prior year financial
      statements have not been restated.

8)          On  January  6,  1998,  the  Company  issued  $230,000,000  of 2.25%
      Convertible Subordinated Debentures with a scheduled maturity in 2013. The
      debentures  are  convertible  into  common  stock  of  the  Company  at  a
      conversion  price of $49.83  per share  subject to  adjustment  in certain
      events.  Debenture holders have the right to require the Company to redeem
      the  debentures  on  January 6, 2004 at a price of  118.968%,  or upon the
      occurrence of a


                                      -9-


                       OMNICOM GROUP INC. AND SUBSIDIARIES
         NOTES TO CONSOLIDATED CONDENSED FINANCIAL STATEMENTS(CONTINUED)

- --------------------------------------------------------------------------------
      
      Fundamental  Change,  as  defined  in  the  indenture  agreement,  at  the
      prevailing  redemption price. The Company may redeem the debentures,  as a
      whole or in part, on or after  December 31, 2001 initially at 112.841% and
      at increasing  prices  thereafter to 118.968%  until January 6, 2004,  and
      100% thereafter.  Unless the debentures are redeemed,  repaid or converted
      prior  thereto,  the  debentures  will  mature on January 6, 2013 at their
      principal amount. The proceeds of this issuance are being used for general
      corporate purposes, including working capital.

9)          On January  29,  1998,  the  Company  announced  that it had reached
      agreement on the terms of a  recommended  cash offer for The GGT Group plc
      ("GGT"),  an advertising and marketing services group headquartered in the
      United Kingdom and operating  primarily in France,  the United Kingdom and
      the United  States.  The offer  price of 200p for each share of GGT valued
      GGT's  fully  diluted   ordinary  share  capital  at  (pound)143   million
      (approximately  $235 million at the January 29, 1998 exchange  rate).  The
      acquisition  of the  entire  issued  ordinary  share  capital  of GGT  was
      completed during the second quarter of 1998.

10)         On March 4, 1998,  the  Company  issued  4,000,000  shares of common
      stock for aggregate proceeds before expenses of $171,400,000. The proceeds
      of this issuance are being used for general corporate purposes,  including
      the funding of the acquisition of GGT.


                                      -10-



                       OMNICOM GROUP INC. AND SUBSIDIARIES
         NOTES TO CONSOLIDATED CONDENSED FINANCIAL STATEMENTS(CONTINUED)

- --------------------------------------------------------------------------------

11)         On June 24, 1998,  the Company  issued French  Francs  1,000,000,000
      (approximately  $164 million at the June 24, 1998  exchange  rate) of 5.2%
      Notes with a scheduled maturity in 2005. The proceeds of this issuance are
      being used for general corporate purposes.


                                      -11-


             Item 2. MANAGEMENT'S DISCUSSION OF FINANCIAL CONDITION
                            AND RESULTS OF OPERATIONS

- --------------------------------------------------------------------------------

Results of Operations
- ---------------------

Second Quarter 1998 Compared to Second Quarter 1997
- ---------------------------------------------------

      Consolidated  worldwide  revenues from commission and fee income increased
33.7% in the second  quarter  of 1998  compared  to the second  quarter of 1997.
Consolidated  domestic revenues increased 35.2% in the second quarter of 1998 to
$550.0  million  compared  to $406.9  million  in the  second  quarter  of 1997.
Consolidated  international  revenues  increased  32.1% in the second quarter of
1998 to $501.5 million compared to $379.4 million in the second quarter of 1997.
Absent the effect of the net acquisitions of subsidiary  companies and movements
in  international  currency  exchange  rates,  consolidated  worldwide  revenues
increased  17.7% in the second  quarter of 1998  compared  to the same period in
1997.

      Operating  expenses increased 32.1% in the second quarter of 1998 compared
to the second  quarter  of 1997.  Excluding  the  effect of the net  acquisition
activity and movements in international currency exchange rates mentioned above,
operating  expenses  increased  15.6% over 1997 levels.  This increase  reflects
normal salary increases and growth in client service expenditures to support the
increased revenue base.


                                      -12-


                 MANAGEMENT'S DISCUSSION OF FINANCIAL CONDITION
                      AND RESULTS OF OPERATIONS (CONTINUED)

- --------------------------------------------------------------------------------

      Net interest  expense  increased by $5.6 million in the second  quarter of
1998 as compared to the same period in 1997.  This increase  primarily  reflects
higher average borrowings during the period, resulting in part from the issuance
of the 2.25% Convertible Subordinated Debentures, partially offset by the effect
of higher average amounts of cash and marketable  securities invested during the
quarter.

      Pretax profit  margin was 15.6% in the second  quarter of 1998 as compared
to 15.0% in the same period in 1997.  Operating margin,  which excludes interest
and dividend  income and interest  expense,  was 16.6% in the second  quarter of
1998 as compared to 15.6% in the same period in 1997.

      The effective  income tax rate was 42.5% in the second  quarter of 1998 as
compared  to 40.7%  in the  second  quarter  of 1997.  This  increase  primarily
reflects an increase in non-deductible goodwill amortization.

      The  reduction  in equity in  affiliates  is the  result of lower  profits
reported by certain  companies  in which the Company owns less than a 50% equity
interest.

      The  increase  in  minority  interest  expense  is  primarily  due  to new
minorities  resulting from  acquisitions and greater earnings by companies where
minority interests exist.

      Net income  increased  29.5% in the second  quarter of 1998 as compared to
the same period in 1997.  Absent the effect of 


                                      -13-


                 MANAGEMENT'S DISCUSSION OF FINANCIAL CONDITION
                      AND RESULTS OF OPERATIONS (CONTINUED)

- --------------------------------------------------------------------------------

net  acquisitions and movements in  international  currency  exchange rates, net
income  increased  15.5% in the second quarter of 1998 as compared to the second
quarter of 1997.

Six Months 1998 Compared to Six Months 1997
- -------------------------------------------

      Consolidated  worldwide  revenues from commission and fee income increased
29.0% in the  first  six  months of 1998  compared  to the same  period in 1997.
Consolidated  domestic revenues  increased 30.0% in the first six months of 1998
to  $1,025.4  million  compared  to $788.5  million in the same  period in 1997.
Consolidated  international  revenues increased 27.8% in the first six months of
1998 to $887.1  million  compared to $694.4  million in the same period in 1997.
Absent the effect of the net acquisitions of subsidiary  companies and movements
in  international  currency  exchange  rates,  consolidated  worldwide  revenues
increased 16.9% in the first six months of 1998 compared to the first six months
of 1997.

      Operating  expenses  increased  27.4% in the first  six  months of 1998 as
compared to the same period in 1997. Excluding the effect of the net acquisition
activity and movements in international currency exchange rates mentioned above,
operating  expenses  increased  16.2% over 1997 levels.  This increase  reflects
normal salary increases and growth in client service expenditures to support the
increased revenue base.


                                      -14-


                 MANAGEMENT'S DISCUSSION OF FINANCIAL CONDITION
                      AND RESULTS OF OPERATIONS (CONTINUED)

- --------------------------------------------------------------------------------

      Net interest expense  increased by $8.8 million in the first six months of
1998 as compared to the same period in 1997.  This increase  primarily  reflects
higher average borrowings during the period, resulting in part from the issuance
of the 2.25% Convertible Subordinated Debentures, partially offset by the effect
of higher average amounts of cash and marketable  securities invested during the
quarter.

      Pretax  profit  margin  for the  first  six  months  of 1998 was  13.4% as
compared to 12.6% in the same period in 1997.  Operating margin,  which excludes
interest and dividend  income and interest  expense,  was 14.3% in the first six
months of 1998 as compared to 13.3% in the same period in 1997.

      The effective income tax rate was 42.1% in the first six months of 1998 as
compared to 40.7% in the same period in 1997. This increase  primarily  reflects
an increase in non-deductible goodwill amortization.

      The  reduction  in equity in  affiliates  is the  result of lower  profits
reported by certain  companies  in which the Company owns less than a 50% equity
interest.

      The  increase  in  minority  interest  expense  is  primarily  due  to new
minorities  resulting from  acquisitions and greater earnings by companies where
minority interests exist.


                                      -15-


                 MANAGEMENT'S DISCUSSION OF FINANCIAL CONDITION
                      AND RESULTS OF OPERATIONS (CONTINUED)

- --------------------------------------------------------------------------------

      Net income  increased 28.6% in the first six months of 1998 as compared to
the same period in 1997.  Absent the effect of net acquisitions and movements in
international  currency  exchange rates, net income increased 15.4% in the first
six months of 1998 as compared to the same period in 1997.

Capital Resources and Liquidity
- -------------------------------

      Cash and cash  equivalents  at June 30, 1998  decreased to $337.9  million
from $556.4 million at December 31, 1997. The  relationship  between payables to
the media and  suppliers  and  receivables  from  clients,  at June 30, 1998, is
consistent with industry norms.

      The  Company  maintains  relationships  with a number of banks  worldwide,
which have extended unsecured committed lines of credit in amounts sufficient to
meet the Company's cash needs.  At June 30, 1998, the Company had $647.0 million
in such  unsecured  committed  lines of credit,  comprised  of a $500.0  million
revolving credit  agreement  expiring June 30, 2003, and $147.0 million in lines
of credit,  principally  outside of the United States.  Of the $647.0 million in
unsecured committed lines, $463.8 million remained available at June 30, 1998.

      On January 6, 1998, the Company issued  $230,000,000 of 2.25%  Convertible
Subordinated  Debentures  with a scheduled  maturity in 2013. The debentures are
convertible into common stock of the Company at a conversion price of $49.83 per
share 


                                      -16-


                 MANAGEMENT'S DISCUSSION OF FINANCIAL CONDITION
                      AND RESULTS OF OPERATIONS (CONTINUED)

- --------------------------------------------------------------------------------

subject to adjustment  in certain  events.  Debenture  holders have the right to
require  the Company to redeem the  debentures  on January 6, 2004 at a price of
118.968%,  or upon the  occurrence  of a Fundamental  Change,  as defined in the
indenture agreement,  at the prevailing redemption price. The Company may redeem
the  debentures,  as a whole or in part, on or after December 31, 2001 initially
at 112.841% and at increasing  prices  thereafter  to 118.968%  until January 6,
2004,  and 100%  thereafter.  Unless  the  debentures  are  redeemed,  repaid or
converted prior thereto,  the debentures will mature on January 6, 2013 at their
principal  amount.  The  proceeds  of this  issuance  are being used for general
corporate purposes, including working capital.

      On March 4, 1998, the Company issued  4,000,000 shares of common stock for
aggregate  proceeds  before  expenses  of  $171,400,000.  The  proceeds  of this
issuance are being used for general corporate purposes, including the funding of
the acquisition of GGT.

      On  June  24,  1998,  the  Company  issued  French  Francs   1,000,000,000
(approximately  $164 million at the June 24, 1998  exchange  rate) of 5.2% Notes
with a scheduled  maturity in 2005. The proceeds of this issuance are being used
for general corporate purposes.

      Management believes the aggregate lines of credit available to the Company
plus cash flows from  operations  will be adequate  to support  its  anticipated
requirements.


                                      -17-


                 MANAGEMENT'S DISCUSSION OF FINANCIAL CONDITION
                      AND RESULTS OF OPERATIONS (CONTINUED)

- --------------------------------------------------------------------------------

Year 2000 Issue
- ---------------

      The Year 2000 issue is the result of computer programs being written using
two digits, rather than four, to define the applicable year. Accordingly, any of
the computer programs utilized by the Company that have date sensitive  software
may cause system failures or miscalculations if data entry of "00" is recognized
as a date other than 2000.

      The Company has determined  that it is required to modify  portions of its
software  so that its  computer  systems  will  properly  utilize  dates  beyond
December 31, 1999. The Company is dependent on third-party  computer systems and
applications,  particularly  with respect to such critical  tasks as accounting,
billing  and  buying,  planning  and  paying  for  media,  as well as on its own
computer systems and internally developed  applications.  The Company intends to
modify or replace all affected  systems for  compliance,  and is also monitoring
the adequacy of the  processes  and progress of  third-party  vendors of systems
that may be  affected by the Year 2000 issue.  The  Company  believes  that with
upgrades or modifications  to existing  software and conversion to new software,
the impact of the Year 2000 issue can be overcome.  However,  if such  upgrades,
modifications  and conversions are not made, or are not made in a timely manner,
the Year 2000 issue could have a material impact on the Company's operations.


                                      -18-


                 MANAGEMENT'S DISCUSSION OF FINANCIAL CONDITION
                      AND RESULTS OF OPERATIONS (CONTINUED)

- --------------------------------------------------------------------------------

      The  Company  will  utilize  both  internal  and  external   resources  to
reprogram,  or replace, and test software for Year 2000 compliance.  The Company
has a team of managers  dedicated to  addressing  Year 2000  compliance  for the
Company,  clients,  and  vendors.  The  costs of the  project  have not yet been
determined  but are  not  expected  to have a  material  adverse  effect  on the
Company.  Amounts  incurred are expected to be expensed as incurred,  unless new
software is purchased  which will be  capitalized.  The Company has not incurred
significant costs to date.


                                      -19-


                           PART II. OTHER INFORMATION

Item 4.  Submission of matters to a Vote of Security Holders

      The Annual Meeting of the  Shareholders of the Company was held on May 18,
1998 in New York,  New York, at which three matters were  submitted to a vote of
the share owners:

      (a) Votes cast for or where  authority to vote for was withheld  regarding
the re-election of six Directors,  five of which for a term expiring in 2001 and
one of which for a term expiring in 1999, were as follows:

                                                               AUTHORITY
                                               FOR              WITHHELD
                                               ---              --------
         (Term Expiring in 2001)
       Bruce Crawford                       145,642,406         1,212,429
       Susan S. Denison                     145,620,158         1,234,677
       Keith L. Reinhard                    142,487,765         4,367,070
       Allen Rosenshine                     145,646,932         1,207,903
       John D. Wren                         145,649,302         1,205,533
         (Term Expiring in 1999)
       Gary L. Roubos                       145,638,268         1,216,567
       
      (b) Votes cast for or against and the number of abstentions  regarding the
confirmation of the  appointment of Arthur Andersen LLP as independent  auditors
of the Company to serve for 1998 were as follows:

         FOR                                146,455,108
         AGAINST                                 85,554
         ABSTAIN                                314,173


                                      -20-


                           PART II. OTHER INFORMATION (CONTINUED)
- --------------------------------------------------------------------------------

Item 4.  Submission of Matters to a Vote of Security Holders (continued)

         (c) Votes cast for or against and the number of  abstentions  regarding
the approval of the 1998 Incentive Compensation Plan were as follows:

         FOR                                  124,398,374
         AGAINST                                6,724,422
         ABSTAIN                                1,177,542

Item 6.  Exhibits

   Exhibit
    Number                          Description of Exhibit
    ------                          ----------------------
     4.1      Copy  of  Fiscal  Agency   Agreement   dated  June  24,  1998,  in
              connection  with the  issuance  of FRF  1,000,000,000  5.20% Notes
              due 2005.

     4.2      Copy of  Subscription  Agreement  dated June 22, 1998 by and among
              Omnicom   Group  Inc.,   Morgan   Stanley  S.A.  and  Others,   in
              connection  with the  issuance  of FRF  1,000,000,000  5.20% Notes
              due 2005.

     4.3      Copy of Deed  of Covenant  dated June 24, 1998, in connection with
              the issuance of FRF 1,000,000,000 5.20% Notes due 2005.

    10.1      Copy of  Omnicom  Group Inc.  1998  Incentive  Compensation  Plan,
              filed as Exhibit A to Omnicom Group Inc.'s Proxy  Statement  dated
              April 6, 1998, is incorporated herein by reference.

    27        Financial Data Schedule (filed in electronic format only)


                                      -21-


SIGNATURES

      Pursuant to the  requirements of the Securities  Exchange Act of 1934, the
registrant  has duly  caused  this  report  to be  signed  on its  behalf by the
undersigned thereunto duly authorized.

                                            Omnicom Group Inc.
                                            (Registrant)
                                            ------------------

Date August 14, 1998                        /s/ Fred J. Meyer
                                            ----------------------
                                            Fred J. Meyer
                                            Chief Financial Officer
                                            (Principal Financial
                                            Officer)

Date August 14, 1998                        /s/ Jonathan E. Ramsden
                                            ----------------------------
                                            Jonathan E. Ramsden
                                            Controller
                                            (Principal Accounting
                                            Officer)


                                      -22-