GUARANTEE AGREEMENT

                                 By and Between

                               OMNICOM GROUP INC.,
                                  as Guarantor

                                       and

                                  ------------,
                                   as Trustee

                          Dated as of ________ __, 200_
<PAGE>

                             Cross Reference Table*

              Section of                         Section of
Trust Indenture Act of 1939, as amended      Guarantee Agreement
---------------------------------------      -------------------

310(a)..................................     4.1
310(b)..................................     2.8; 4.1
310(c)..................................     Inapplicable
311(a)..................................     2.2(b)
311(b)..................................     2.2(b)
311(c)..................................     Inapplicable
312(a)..................................     2.2(a); 2.9
312(b)..................................     2.2(b); 2.9
312(c)..................................     2.9
313(a)..................................     2.3
313(b)..................................     2.3
313(c)..................................     2.3
313(d)..................................     2.3
314(a)..................................     2.4
314(b)..................................     Inapplicable
314(c)..................................     2.5
314(d)..................................     Inapplicable
314(e)..................................     2.5; 1.1
314(f)..................................     Inapplicable
315(a)..................................     3.1(d)
315(b)..................................     2.7(a)
315(c)..................................     3.1(c)
315(d)..................................     3.1(e)
316(a)..................................     2.6; 5.4(a)
316(b)..................................     5.3
316(c)..................................     Inapplicable
317(a)..................................     2.10
317(b)..................................     Inapplicable
318(a)..................................     2.1(b)
318(b)..................................     2.1
318(c)..................................     2.1(a)

----------
*   This cross-reference table does not constitute part of the agreement and
    shall not have any bearing upon the interpretation of any of its terms or
    provisions.
<PAGE>

                                Table of Contents

ARTICLE I INTERPRETATION AND DEFINITIONS ..................................    1

   Section 1.1  Definitions ...............................................    1
   Section 1.2  Incorporation by Reference of Trust Indenture Act .........    5
   Section 1.3  Rules of Construction .....................................    5

ARTICLE II TRUST INDENTURE ACT ............................................    5

   Section 2.1  Trust Indenture Act; Application ..........................    5
   Section 2.2  Lists of Holders ..........................................    6
   Section 2.3  Reports by Guarantee Trustee ..............................    6
   Section 2.4  Periodic Reports to Guarantee Trustee .....................    6
   Section 2.5  Evidence of Compliance with Conditions Precedent ..........    6
   Section 2.6  Guarantee Event of Default; Waiver ........................    7
   Section 2.7  Guarantee Event of Default; Notice ........................    7
   Section 2.8  Conflicting Interests .....................................    7
   Section 2.9  Disclosure of Information .................................    7
   Section 2.10 Guarantee Trustee May File Proofs of Claim ................    7

ARTICLE III POWERS, DUTIES AND RIGHTS OF GUARANTEE TRUSTEE ................    8

   Section 3.1  Duties of Guarantee Trustee ...............................    8
   Section 3.2  Rights of Guarantee Trustee ...............................    9
   Section 3.3  Guarantee Trustee's Disclaimer ............................   10

ARTICLE IV GUARANTEE TRUSTEE ..............................................   11

   Section 4.1  Eligibility; Disqualification .............................   11
   Section 4.2  Replacement of Guarantee Trustee ..........................   11

ARTICLE V GUARANTEE .......................................................   12

   Section 5.1  Guarantee .................................................   12
   Section 5.2  Waiver of Notice and Demand ...............................   12
   Section 5.3  Obligations Not Affected ..................................   13
   Section 5.4  Rights of Holders .........................................   14
   Section 5.5  Guarantee of Payment ......................................   14
   Section 5.6  Subrogation ...............................................   14
   Section 5.7  Independent Obligations ...................................   15

ARTICLE VI LIMITATION OF TRANSACTIONS; SUBORDINATION ......................   15

   Section 6.1  Limitation of Transactions ................................   15
   Section 6.2  Ranking ...................................................   16

ARTICLE VII TERMINATION ...................................................   16

   Section 7.1  Termination ...............................................   16

ARTICLE VIII INDEMNIFICATION ..............................................   16

   Section 8.1  Exculpation ...............................................   16
   Section 8.2  Compensation and Indemnity ................................   17
<PAGE>

ARTICLE IX MISCELLANEOUS ..................................................   17

   Section 9.1  Successors and Assigns ....................................   17
   Section 9.2  Amendments ................................................   18
   Section 9.3  Notices ...................................................   18
   Section 9.4  Counterparts ..............................................   19
   Section 9.5  Benefit ...................................................   19
   Section 9.6  Governing Laws ............................................   19
<PAGE>

                               GUARANTEE AGREEMENT

      WHEREAS, pursuant to the Trust Agreement (as defined herein), the Omnicom
Capital Trust [I / II / III] (the "Trust") is issuing on the date hereof
$________ aggregate liquidation amount of preferred securities, having a
liquidation amount of $____ per security and designated the "____% Trust
Preferred Securities" [OR INSERT OTHER DESIGNATION] of the Trust (the "Trust
Preferred Securities") and $________ aggregate liquidation amount of common
securities, having a liquidation amount of $____ per security and designated the
"____% Trust Common Securities" of the Trust (together with the Trust Preferred
Securities, the "Trust Securities");

      WHEREAS, as incentive for the Holders (as defined herein) to purchase the
Trust Preferred Securities, Omnicom Group, Inc. (the "Guarantor") desires
irrevocably and unconditionally to agree, to the extent set forth in this
Guarantee, to pay to the Holders of the Trust Preferred Securities the Guarantee
Payments (as defined herein) and to make certain other payments on the terms and
conditions set forth herein; and

      NOW, THEREFORE, in consideration of the purchase by each Holder of Trust
Preferred Securities, which purchase the Guarantor hereby agrees shall benefit
the Guarantor, the Guarantor executes and delivers this Guarantee for the
benefit of such Holders.

                                   ARTICLE I
                         INTERPRETATION AND DEFINITIONS

      Section 1.1 Definitions.

      "Affiliate" of any specified person means any other person directly or
indirectly controlling or controlled by or under direct or indirect common
control with such specified person. For the purposes of this definition,
"control" (including, with correlative meanings, the terms "controlled by" and
"under common control with"), as used with respect to any person, shall mean the
possession, directly or indirectly, of the power to direct or cause the
direction of the management or policies of such person, whether through the
ownership of voting securities or by agreement or otherwise.

      "Beneficial Owners" has the meaning specified in the Trust Agreement.

      "Business Day" has the meaning specified in the Trust Agreement.

      "Corporate Trust Office" means the office of the Guarantee Trustee at
which at any particular time its corporate trust business shall be principally
administered, which office at the date of execution of this Guarantee is located
at ________, ________, ________, ________, Attention: __________.

      "Covered Person" means a Holder or beneficial owner of Trust Preferred
Securities.
<PAGE>

      "Depositary" has the meaning specified in the Trust Agreement.

      "Depositary Participants" has the meaning specified in the Trust
Agreement.

      "Distribution" has the meaning specified in the Trust Agreement.

      "Event of Default" has the meaning specified in the Indenture.

      "Global Certificate" has the meaning specified in the Trust Agreement.

      "Global Security" means a fully registered, global Preferred Security
representing the Trust Preferred Securities.

      "Guarantee Event of Default" means a default by the Guarantor on any of
its payment or other obligations under this Guarantee.

      "Guarantee Payments" means the following payments or distributions,
without duplication, with respect to the Trust Preferred Securities, to the
extent not paid by or on behalf of the Trust: (i) any accrued and unpaid
Distributions that are required to be paid on such Trust Preferred Securities to
the extent the Trust has sufficient funds legally and immediately available
therefor at the time, (ii) the Redemption Price, including all accrued and
unpaid Distributions to the date of redemption, with respect to any Trust
Preferred Securities called for redemption by the Trust, to the extent the Trust
shall have sufficient funds legally and immediately available therefor at the
time or (iii) upon a voluntary or involuntary dissolution, winding-up or
termination of the Trust (other than in connection with the distribution of
Junior Subordinated Debt Securities to the holders of Trust Securities as
provided in the Trust Agreement or the redemption of all the Trust Preferred
Securities), the lesser of (a) the sum of the liquidation amount and all accrued
and unpaid Distributions on the Trust Preferred Securities to the date of
payment, to the extent the Trust has sufficient funds legally and immediately
available therefor and (b) the amount of assets of the Trust remaining available
for distribution to Holders of Trust Preferred Securities in liquidation of the
Trust (in either case, the "Liquidation Distribution").

      "Guarantee Trustee" means ________, until a successor Guarantee Trustee
has been appointed and has accepted such appointment pursuant to the terms of
this Guarantee and thereafter means each such Successor Guarantee Trustee.

      "Guarantor" has the meaning specified in the recitals hereto.

      "Holder" means a person in whose name any of the Trust Preferred
Securities is registered; provided, however, that, in determining whether the
Holders of the requisite percentage of Trust Preferred Securities have given any
request, notice, consent or waiver hereunder, "Holder" shall not include the
Guarantor or any Affiliate of the Guarantor or any other obligor on the Trust
Preferred Securities; and provided further that in determining whether the
Holders of the requisite liquidation amount of Trust Preferred Securities have
voted on any matter provided for in this Guarantee, then for the purpose of such
determination only (and not for any other purpose hereunder), if the Trust

<PAGE>

Preferred Securities remain in the form of one or more Global Certificates and
if the Depositary which is the holder of such Global Securities has sent an
omnibus proxy to the Trust assigning voting rights to Depositary Participants to
whose accounts the Trust Preferred Securities are credited on the record date,
the term "Holders" shall mean such Depositary Participants acting at the
direction of the Beneficial Owners.

      "Indemnified Person" means the Guarantee Trustee, or any officers,
directors, employees, shareholders or agents of the Guarantee Trustee.

      "Indenture" means the Junior Subordinated Indenture, dated as of ________
__, 200_, by and between Omnicom Group Inc. and ________, as Trustee, as
supplemented and amended by a First Supplemental Indenture dated as of ________
__, 200_, pursuant to which the Junior Subordinated Debt Securities are to be
issued to the Property Trustee.

      "Junior Subordinated Debt Securities" means the series of junior
subordinated debt securities to be issued by Omnicom Group Inc. designated the
"____% Junior Subordinated Debt Securities due ____" held by the Property
Trustee.

      "List of Holders" has the meaning assigned to it in Section 2.2 hereof.

      "Majority in Liquidation Amount" means Holders of outstanding Trust
Preferred Securities, voting separately as a class, who are the record owners of
more than 50% of the aggregate liquidation amount (including the stated amount
that would be paid on redemption, liquidation or otherwise, plus accrued and
unpaid Distributions to the date upon which the voting percentages are
determined) of all outstanding Trust Preferred Securities. In determining
whether the Holders of the requisite amount of Trust Preferred Securities have
voted, Trust Preferred Securities which are owned by the Guarantor or any
Affiliate of the Guarantor or any other obligor on the Trust Preferred
Securities shall be disregarded for the purpose of any such determination.

      "Officer" means the Chairman of the Board, the Chief Executive Officer,
the Chief Operating Officer, the Chief Financial Officer, any Vice-President,
the Treasurer, the Secretary, any Assistant Treasurer or any Assistant Secretary
of the Guarantor.

      "Officers' Certificate" means a certificate signed by two Officers, one of
whom must be the Guarantor's principal executive officer, principal financial
officer or principal accounting officer. Any Officers' Certificate delivered
with respect to compliance with a condition or covenant provided for in this
Guarantee (other than pursuant to Section 314(a)(4) of the TIA) shall include:

            (a) a statement that each officer signing the Officers' Certificate
      has read the covenant or condition and the definitions relating thereto;

            (b) a brief statement of the nature and scope of the examination or
      investigation undertaken by each officer on behalf of such person in
      rendering the Officers' Certificate;
<PAGE>

            (c) a statement that each such officer has made such examination or
      investigation as, in such officer's opinion, is necessary to enable such
      officer on behalf of such person to express an informed opinion as to
      whether or not such covenant or condition has been complied with; and

            (d) a statement as to whether, in the opinion of each such officer
      acting on behalf of such person, such condition or covenant has been
      complied with.

      "person" means any individual, corporation, partnership, joint venture,
association, limited liability company, joint-stock company, trust,
unincorporated organization, or government or any agency or political
subdivision thereof.

      "Property Trustee" has the meaning specified in the Trust Agreement.

      "Redemption Price" has the meaning specified in the Trust Agreement.

      "Registrar" has the meaning specified in the Indenture.

      "Responsible Officer" means, with respect to the Guarantee Trustee, any
officer with direct responsibility for the administration of this Guarantee and
also means, with respect to a particular corporate trust matter, any other
officer to whom any corporate trust matter is referred because of his or her
knowledge of and familiarity with a particular subject.

      "Senior Indebtedness" has the meaning specified in the Indenture.

      "Sponsor" has the meaning specified in the Trust Agreement.

      "Successor Guarantee Trustee" means a successor Guarantee Trustee
possessing the qualifications to act as Guarantee Trustee under Section 4.1.

      "Trust" has the meaning specified in the recitals hereto.

      "Trust Agreement" means the Amended and Restated Trust Agreement, dated as
of __________ __, ____, as amended, modified or supplemented from time to time,
among the trustees of the Trust named therein, the Guarantor, as sponsor, and
the Holders, from time to time, of undivided beneficial ownership interests in
the assets of the Trust.

      "Trust Preferred Securities" has the meaning specified in the recitals
hereto. In the event that pursuant to the Trust Agreement, the Trust and the
Sponsor grant an Option (as defined in Section 7.18 of the Trust Agreement) to
certain underwriters or initial purchasers, as the case may be, such that an
additional amount of Trust Preferred Securities may be issued pursuant to the
terms of the Trust Agreement, then the defined term "Trust Preferred Securities"
shall include such additional Trust Preferred Securities.

      "Trust Securities" has the meaning specified in the recitals hereto.
<PAGE>

      "TIA" means the TIA of 1939 (15 U.S. Code ss.ss.. 77aaa-77bbbb), as
amended from time to time, and as in effect on the date of this Guarantee;
provided, however, that in the event the TIA is amended after such date, TIA
means, to the extent required by any such amendment, the TIA as so amended.

      Section 1.2 Incorporation by Reference of Trust Indenture Act.

      Whenever this Guarantee refers to a provision of the TIA, the provision is
incorporated by reference in and made a part of this Guarantee. All terms used
in this Guarantee that are defined by the TIA, defined by the TIA's reference to
another statute or defined by Securities and Exchange Commission rule under the
TIA and not otherwise defined herein are used herein as so defined.

      Section 1.3 Rules of Construction.

      Unless the context otherwise requires:

            (a) a term has the meaning assigned to it;

            (b) "or" is not exclusive;

            (c) words in the singular include the plural, and in the plural
      include the singular; and

            (d) provisions apply to successive events and transactions.

                                   ARTICLE II
                               TRUST INDENTURE ACT

      Section 2.1 Trust Indenture Act; Application.

            (a) This Guarantee is subject to the provisions of the TIA that are
      required to be part of this Guarantee and shall, to the extent applicable,
      be governed by such provisions.

            (b) If and to the extent that any provision of this Guarantee
      limits, qualifies or conflicts with the duties imposed by Sections 310 to
      317, inclusive, of the TIA, such imposed duties shall control.

      Section 2.2 Lists of Holders.

            (a) The Guarantor shall furnish to the Guarantee Trustee a list of
      the names and addresses of the Holders ("List of Holders") in such form
      and as of such date as the Guarantee Trustee may reasonably require. The
      Guarantor shall furnish such List of Holders (i) within 30 days after
      receiving a written request from the Guarantee Trustee, such list to be as
      of a date no more than 15 days before such list is provided to the
      Guarantee Trustee, and (ii) unless the Trust Preferred Securities are
      represented by one or more Global Securities, at least one

<PAGE>

      Business Day prior to the date for payment of Distributions, such list to
      be as of the record date relating to the payment of such Distributions.
      However, the Guarantor shall not be obligated to provide such List of
      Holders at any time the List of Holders does not differ from the most
      recent List of Holders given to the Guarantee Trustee by the Guarantor or
      at any time the Guarantee Trustee is the Registrar under the Trust
      Agreement. The Guarantee Trustee shall preserve, in as current a form as
      is reasonably practicable, all information contained in Lists of Holders
      given to it, provided that the Guarantee Trustee may destroy any List of
      Holders previously given to it on receipt of a new List of Holders.

            (b) The Guarantee Trustee shall comply with its obligations under
      Sections 311(a), 311(b) and 312(b) of the TIA.

      Section 2.3 Reports by Guarantee Trustee.

      Within 60 days after September 15 of each year (commencing with the year
of the first anniversary of the issuance of the Trust Preferred Securities), the
Guarantee Trustee shall provide to the Holders such reports as are required by
Section 313(a) of the TIA (if any) in the form and in the manner provided by
Section 313 of the TIA. The Guarantee Trustee shall also comply with the other
requirements of Section 313 of the TIA. The Guarantor shall promptly notify the
Guarantee Trustee when the Trust Preferred Securities are listed on any stock
exchange.

      Section 2.4 Periodic Reports to Guarantee Trustee.

      The Guarantor shall provide to the Guarantee Trustee such documents,
reports and information as required by Section 314(a) (if any) of the TIA and
the compliance certificate required by Section 314(a)(4) of the TIA in the form,
in the manner and at the times required by Section 314(a) of the TIA, provided
that such compliance certificate shall be delivered on or before 120 days after
the end of each calendar year of the Guarantor.

      Section 2.5 Evidence of Compliance with Conditions Precedent.

      The Guarantor shall provide to the Guarantee Trustee such evidence of
compliance with any conditions precedent, if any, provided for in this Guarantee
that relate to any of the matters set forth in Section 314(c) of the TIA. Any
certificate or opinion required to be given by an officer pursuant to Section
314(c)(1) may be given in the form of an Officers' Certificate.

      Section 2.6 Guarantee Event of Default; Waiver.

      The Holders of a Majority in Liquidation Amount of the Trust Preferred
Securities may, by vote or written consent, on behalf of all of the Holders,
waive any past Guarantee Event of Default and its consequences. Upon such
waiver, any such Guarantee Event of Default shall cease to exist, and any
Guarantee Event of Default arising therefrom shall be deemed to have been cured,
for every purpose of this

<PAGE>

Guarantee, but no such waiver shall extend to any subsequent or other default or
Guarantee Event of Default or impair any right consequent thereon.

      Section 2.7 Guarantee Event of Default; Notice.

      If a Guarantee Event of Default occurs and is continuing and if it is
known to a Responsible Officer of the Guarantee Trustee, the Guarantee Trustee
shall mail to each Holder notice of a Guarantee Event of Default within 90 days
after it occurs or, if later, after a Responsible Officer of the Guarantee
Trustee has knowledge of such Guarantee Event of Default. The Guarantee Trustee
may withhold the notice if and so long as its corporate trust committee or a
committee of its Responsible Officers in good faith determines that withholding
the notice is in the interests of the Holders.

      Section 2.8 Conflicting Interests.

      The Trust Agreement shall be deemed to be specifically described in this
Guarantee for the purposes of clause (i) of the first proviso contained in
Section 310(b) of the TIA.

      Section 2.9 Disclosure of Information.

      The disclosure of information as to the names and addresses of the Holders
in accordance with Section 312 of the TIA, regardless of the source from which
such information was derived, shall not be deemed to be a violation of any
existing law, or any law hereafter enacted which does not specifically refer to
Section 312 of the TIA, nor shall the Guarantee Trustee be held accountable by
reason of mailing any material pursuant to a request made under Section 312(b)
of the TIA.

      Section 2.10 Guarantee Trustee May File Proofs of Claim.

      Upon the occurrence of a Guarantee Event of Default, the Guarantee Trustee
is hereby authorized to (a) recover judgment, in its own name and as trustee of
an express trust, against the Guarantor for the whole amount of any Guarantee
Payments remaining unpaid and (b) file such proofs of claim and other papers or
documents as may be necessary or advisable in order to have its claims and those
of the Holders allowed in any judicial proceedings relative to the Guarantor,
its creditors or its property.

                                  ARTICLE III
                 POWERS, DUTIES AND RIGHTS OF GUARANTEE TRUSTEE

      Section 3.1 Duties of Guarantee Trustee.

            (a) This Guarantee shall be held by the Guarantee Trustee on behalf
      of the Trust for the benefit of the Holders, and the Guarantee Trustee
      shall not transfer this Guarantee to any Person except a Holder exercising
      his or her rights pursuant to Section 5.4(b) or to a Successor Guarantee
      Trustee on acceptance by such Successor Guarantee Trustee of its
      appointment to act as Successor

<PAGE>

      Guarantee Trustee. The right, title and interest of the Guarantee Trustee
      in and to this Guarantee shall automatically vest in any Successor
      Guarantee Trustee, and such vesting and succession of title shall be
      effective upon acceptance of appointment whether or not conveyance
      documents have been executed and delivered pursuant to the appointment of
      such Successor Guarantee Trustee.

            (b) If a Guarantee Event of Default has occurred and is continuing,
      the Guarantee Trustee shall enforce this Guarantee for the benefit of the
      Holders.

            (c) If a Guarantee Event of Default has occurred and is continuing,
      the Guarantee Trustee shall exercise the rights and powers vested in it by
      this Guarantee and use the same degree of care and skill in its exercise
      thereof as a prudent man would exercise or use under the circumstances in
      the conduct of his own affairs.

            (d) Except during the continuance of any Guarantee Event of Default:

            (i) The Guarantee Trustee need perform only those duties that are
      specifically set forth in this Guarantee and no others.

            (ii) In the absence of bad faith on its part, the Guarantee Trustee
      may conclusively rely, as to the truth of the statements and the
      correctness of the opinions expressed therein, upon Officers' Certificates
      or opinions of counsel furnished to the Guarantee Trustee and conforming
      to the requirements of this Guarantee; however, in the case of any such
      Officers' Certificates or opinions of counsel which by any provisions
      hereof are specifically required to be furnished to the Guarantee Trustee,
      the Guarantee Trustee shall examine such Officers' Certificates and
      opinions of counsel to determine whether or not they conform to the
      requirements of this Guarantee.

            (e) The Guarantee Trustee may not be relieved from liability for its
      own negligent action, its own negligent failure to act, or its own willful
      misconduct, except that:

            (i) This paragraph does not limit the effect of paragraph (d) of
      this Section.

            (ii) The Guarantee Trustee shall not be liable for any error of
      judgment made in good faith by a Responsible Officer, unless it shall be
      proved that the Guarantee Trustee was negligent in ascertaining the
      pertinent facts.

            (iii) The Guarantee Trustee shall not be liable with respect to any
      action taken or omitted to be taken by it with respect to the Trust
      Preferred Securities in good faith in accordance with the direction of the
      Holders of not less than a Majority in Liquidation Amount of the Trust
      Preferred Securities relating to the time, method and place of conducting
      any proceeding for any remedy available to the Guarantee Trustee or
      exercising any trust or power conferred upon the

<PAGE>

      Guarantee Trustee under this Guarantee with respect to the Trust Preferred
      Securities.

            (f) Every provision of this Guarantee that in any way relates to the
      Guarantee Trustee is subject to paragraphs (c), (d) and (e) of this
      Section.

            (g) The Guarantee Trustee may refuse to perform any duty or exercise
      any right or power unless it receives indemnity satisfactory to it against
      any loss, liability or expense.

            (h) The Guarantee Trustee shall not be liable for interest on any
      money received by it except as the Guarantee Trustee may agree in writing
      with the Guarantor. Money held in trust by the Guarantee Trustee need not
      be segregated from other funds except to the extent required by law.

            (i) No provision of this Guarantee shall require the Guarantee
      Trustee to risk its own funds or otherwise incur any financial liability
      in the performance of any of its duties, or in the exercise of any of its
      rights or powers, if the Guarantee Trustee shall have reasonable grounds
      for believing that the repayment of such funds or adequate indemnity
      against such risk is not reasonably assured to it.

      Section 3.2 Rights of Guarantee Trustee.

            (a) The Guarantee Trustee may rely on and shall be protected in
      acting or refraining from acting upon, any document believed by it to be
      genuine and to have been signed or presented by the proper person. The
      Guarantee Trustee need not investigate any fact or matter stated in the
      document.

            (b) Before the Guarantee Trustee acts or refrains from acting, it
      may require an Officers' Certificate or an opinion of counsel. The
      Guarantee Trustee shall not be liable for any action it takes or omits to
      take in good faith in reliance on such Officers' Certificate or opinion of
      counsel.

            (c) The Guarantee Trustee may act through agents and shall not be
      responsible for the misconduct or negligence of any agent appointed with
      due care. No Depositary shall be deemed an agent of the Guarantee Trustee
      and the Guarantee Trustee shall not be responsible for any act or omission
      by any Depositary.

            (d) The Guarantee Trustee shall not be liable for any action it
      takes or omits to take in good faith which it believes to be authorized or
      within its rights or powers.

            (e) The Guarantee Trustee may consult with counsel and the advice of
      such counsel or any opinion of counsel shall be full and complete
      authorization and protection in respect of any action taken, suffered or
      omitted by it hereunder in good faith and in reliance thereon.
<PAGE>

            (f) The Guarantee Trustee shall be under no obligation to exercise
      any of the rights or powers vested in it by this Guarantee at the request
      or direction of any of the Holders unless such Holders shall have offered
      to the Guarantee Trustee reasonable security or indemnity against the
      costs, expenses and liabilities which might be incurred by it in
      compliance with such request or direction, including such reasonable
      advances as may be requested by the Guarantee Trustee; provided, that
      nothing contained in this Section 3.2(f) shall be taken to relieve the
      Guarantee Trustee, upon the occurrence of a Guarantee Event of Default, of
      its obligation to exercise the rights and powers vested in it by this
      Guarantee in the manner provided by Section 3.1(c).

            (g) Whenever in the administration of this Guarantee, the Guarantee
      Trustee shall deem it desirable to receive instructions with respect to
      enforcing any remedy or right or taking any other action hereunder, the
      Guarantee Trustee (A) may request written instructions from the Holders of
      a Majority in Liquidation Amount of the Trust Preferred Securities, (B)
      may refrain from enforcing such remedy or right or taking such other
      action until such written instructions are received and (C) shall be
      protected in conclusively relying on or acting in accordance with such
      written instructions.

            (h) No provision of this Guarantee shall be deemed to impose any
      duty or obligation on the Guarantee Trustee to perform any act or acts or
      exercise any right, power, duty or obligation conferred or imposed on it
      in any jurisdiction in which it shall be illegal, or in which the
      Guarantee Trustee shall be unqualified or incompetent to act in accordance
      with applicable law, to perform any such act or acts or to exercise any
      such right, power, duty or obligation. No permissive power or authority
      available to the Guarantee Trustee shall be construed to be a duty.

      Section 3.3 Guarantee Trustee's Disclaimer.

      The Guarantee Trustee makes no representation as to the validity or
adequacy of this Guarantee or the Trust Preferred Securities, and it shall not
be responsible for any statement in the Securities other than its authentication
of the Trust Preferred Securities.

                                   ARTICLE IV
                                GUARANTEE TRUSTEE

      Section 4.1 Eligibility; Disqualification.

      This Guarantee shall always have a Guarantee Trustee who satisfies the
requirements of Sections 310(a)(1), (2) and (5) of the TIA. The Guarantee
Trustee shall always have a combined capital and surplus of at least $25,000,000
as set forth in its most recent published annual report of condition. The
Guarantee Trustee shall comply with Section 310(b) of the TIA.
<PAGE>

      Section 4.2 Replacement of Guarantee Trustee.

            (a) A resignation or removal of the Guarantee Trustee and
      appointment of a successor Guarantee Trustee shall become effective only
      upon the successor Guarantee Trustee's acceptance of appointment as
      provided in this Section.

            (b) The Guarantee Trustee may resign by so notifying the Guarantor.
      The Holders of a Majority in Liquidation Amount of the Trust Preferred
      Securities may remove the Guarantee Trustee by so notifying the Guarantee
      Trustee and the Guarantor. The Guarantor may remove the Guarantee Trustee
      if:

            (i) the Guarantee Trustee fails to comply with Section 4.1;

            (ii) the Guarantee Trustee is adjudged a bankrupt or an insolvent or
      an order for relief is entered with respect to the Guarantee Trustee under
      any Bankruptcy Law;

            (iii) a custodian or public officer takes charge of the Guarantee
      Trustee or its property; or

            (iv) the Guarantee Trustee becomes incapable of acting.

            (c) If the Guarantee Trustee resigns or is removed or if a vacancy
      exists in the office of Guarantee Trustee for any reason, the Guarantor
      shall promptly appoint a Successor Guarantee Trustee. Within one year
      after the Successor Guarantee Trustee takes office, the Holders of a
      Majority in Liquidation Amount of the then outstanding Trust Preferred
      Securities may appoint a Successor Guarantee Trustee to replace the
      Successor Guarantee Trustee appointed by the Guarantor.

            (d) If a Successor Guarantee Trustee does not take office within 60
      days after the retiring Guarantee Trustee resigns or is removed, the
      retiring Guarantee Trustee, the Guarantor or the Holders of at least 10%
      in Liquidation Amount of the Trust Preferred Securities may petition any
      court of competent jurisdiction for the appointment of a Successor
      Guarantee Trustee.

            (e) If the Guarantee Trustee fails to comply with Section 4.1, any
      Holder may petition any court of competent jurisdiction for the removal of
      the Guarantee Trustee and the appointment of a Successor Guarantee
      Trustee.

            (f) A Successor Guarantee Trustee shall deliver a written acceptance
      of its appointment to the retiring Guarantee Trustee and to the Guarantor.
      Immediately after that, the retiring Guarantee Trustee shall transfer all
      property held by it as Guarantee Trustee to the Successor Guarantee
      Trustee, the resignation or removal of the retiring Guarantee Trustee
      shall become effective, and the Successor Guarantee Trustee shall have all
      the rights, powers and duties of the Guarantee Trustee under this
      Guarantee. A Successor Guarantee Trustee

<PAGE>

      shall mail a notice of its succession to each Holder. Notwithstanding
      replacement of the Guarantee Trustee pursuant to this Section 4.2, the
      Guarantor's obligations under Section 8.2 hereof shall continue for the
      benefit of the retiring Guarantee Trustee with respect to expenses and
      liabilities incurred by it prior to such replacement.

                                   ARTICLE V
                                    GUARANTEE

      Section 5.1 Guarantee.

      The Guarantor irrevocably and unconditionally agrees to pay in full to the
Holders the Guarantee Payments (without duplication of amounts theretofore paid
by the Trust), as and when due, regardless of any defense, right of set-off or
counterclaim that the Guarantor may have or assert against any person. The
Guarantor's obligation to make a Guarantee Payment may be satisfied by direct
payment of the required amounts by the Guarantor to the Holders or by causing
the Trust to pay such amounts to the Holders. Notwithstanding anything to the
contrary herein, the Guarantor retains all of its rights under the Indenture to
(i) extend the interest payment period on the Junior Subordinated Debt
Securities pursuant to Section 2.10 thereof and the Guarantor shall not be
obligated hereunder to make any Guarantee Payments during any Extension Period
with respect to the Distributions on the Securities and (ii) change the maturity
date of the Junior Subordinated Debt Securities to the extent permitted by the
Indenture.

      Section 5.2 Waiver of Notice and Demand.

      The Guarantor hereby waives notice of acceptance of this Guarantee and of
any liability to which it applies or may apply, presentment, demand for payment,
any right to require a proceeding first against the Trust or any other Person
before proceeding against the Guarantor, protest, notice of nonpayment, notice
of dishonor, notice of redemption and all other notices and demands.

      Section 5.3 Obligations Not Affected.

      The obligations, covenants, agreements and duties of the Guarantor under
this Guarantee shall be absolute and unconditional and shall remain in full
force and effect until the entire liquidation amount of all outstanding Trust
Preferred Securities shall have been paid and such obligation shall in no way be
affected or impaired by reason of the happening from time to time of any event,
including without limitation, the following, whether or not with notice to, or
the consent of, the Guarantor:

            (a) The release or waiver, by operation of law or otherwise, of the
      performance or observance by the Trust of any express or implied
      agreement, covenant, term or condition relating to the Trust Preferred
      Securities to be performed or observed by the Trust;
<PAGE>

            (b) The extension of time for the payment by the Trust of all or any
      portion of the Distributions, Redemption Price, Liquidation Distribution
      or any other sums payable under the terms of the Trust Preferred
      Securities or the extension of time for the performance of any other
      obligation under, arising out of, or in connection with the Trust
      Preferred Securities (other than an extension of time for payment of
      Distributions, Redemption Price, Liquidation Distribution or other sum
      payable that results from the extension of any interest payment period on
      the Junior Subordinated Debt Securities or any change to the maturity date
      of the Junior Subordinated Debt Securities permitted by the Indenture);

            (c) Any failure, omission, delay or lack of diligence on the part of
      the Property Trustee or the Holders to enforce, assert or exercise any
      right, privilege, power or remedy conferred on the Property Trustee or the
      Holders pursuant to the terms of the Trust Preferred Securities, or any
      action on the part of the Trust granting indulgence or extension of any
      kind;

            (d) The voluntary or involuntary liquidation, dissolution, sale of
      any collateral, receivership, insolvency, bankruptcy, assignment for the
      benefit of creditors, reorganization, arrangement, composition or
      readjustment of debt of, or other similar proceedings affecting, the Trust
      or any of the assets of the Trust;

            (e) Any invalidity of, or defect or deficiency in, the Trust
      Preferred Securities;

            (f) The settlement or compromise of any obligation guaranteed hereby
      or hereby incurred; or

            (g) Any other circumstance whatsoever that might otherwise
      constitute a legal or equitable discharge or defense of a guarantor, it
      being the intent of this Section 5.3 that the obligations of the Guarantor
      hereunder shall be absolute and unconditional under any and all
      circumstances.

There shall be no obligation of the Guarantee Trustee or the Holders to give
notice to or obtain consent of the Guarantor or any other Person with respect to
the happening of any of the foregoing. No setoff, counterclaim, reduction or
diminution of any obligation, or any defense of any kind or nature that the
Guarantor has or may have against any Holder shall be available hereunder to the
Guarantor against such Holder to reduce the payments to it under this Guarantee.

      Section 5.4 Rights of Holders.

            (a) The Holders of at least a Majority in Liquidation Amount of the
      Trust Preferred Securities have the right to direct the time, method and
      place of conducting any proceeding for any remedy available to the
      Guarantee Trustee in respect of this Guarantee or to direct the exercise
      of any trust or power conferred upon the Guarantee Trustee under this
      Guarantee, provided, that, subject to Section 3.1, the Guarantee Trustee
      shall have the right to decline to follow any such direction if: (i) the
      Guarantee Trustee shall determine that the action so

<PAGE>

      directed would be unjustly prejudicial to the Holders not taking part in
      such direction, (ii) the Guarantee Trustee being advised by counsel
      determines that the action or proceeding so directed may not lawfully be
      taken or (iii) the Guarantee Trustee in good faith by its board of
      directors or trustees, executive committee, or a trust committee of
      directors or trustees and/or Responsible Officers shall determine that the
      action or proceedings so directed would involve the Guarantee Trustee in
      personal liability.

            (b) If the Guarantee Trustee fails to enforce this Guarantee, then
      any Holder may, subject to the subordination provisions of Section 6.2,
      institute a legal proceeding directly against the Guarantor to enforce the
      Guarantee Trustee's rights under this Guarantee without first instituting
      a legal proceeding against the Trust, the Guarantee Trustee or any other
      person or entity. In addition, if the Guarantor has failed to make a
      Guarantee Payment, a Holder may, subject to the subordination provisions
      of Section 6.2, directly institute a proceeding against the Guarantor for
      enforcement of the Guarantee for such payment to the Holder of the
      principal of or interest on the Junior Subordinated Debt Securities on or
      after the respective due dates specified in the Junior Subordinated Debt
      Securities, and the amount of the payment will be based on the Holder's
      pro rata share of the amount due and owing on all of the Trust Preferred
      Securities. The Guarantor hereby waives any right or remedy to require
      that any action on this Guarantee be brought first against the Trust or
      any other person or entity before proceeding directly against the
      Guarantor.

      Section 5.5 Guarantee of Payment.

      This Guarantee creates a guarantee of payment and not of collection.

      Section 5.6 Subrogation.

      The Guarantor shall be subrogated to all (if any) rights of the Holders
against the Trust in respect of any amounts paid to such Holders by the
Guarantor under this Guarantee; provided, however, that the Guarantor shall not
(except to the extent required by mandatory provisions of law) be entitled to
enforce or exercise any right that it may acquire by way of subrogation or any
indemnity, reimbursement or other agreement, in all cases as a result of payment
under this Guarantee, if at the time of any such payment, any amounts are due
and unpaid under this Guarantee. If any amount shall be paid to the Guarantor in
violation of the preceding sentence, the Guarantor agrees to hold such amount in
trust for the Holders and to pay over such amount to the Guarantee Trustee for
the benefit of the Holders.

      Section 5.7 Independent Obligations.

      The Guarantor acknowledges that its obligations hereunder are independent
of the obligations of the Trust with respect to the Trust Preferred Securities,
and that the Guarantor shall be liable as principal and as debtor hereunder to
make Guarantee

<PAGE>

Payments pursuant to the terms of this Guarantee notwithstanding the occurrence
of any event referred to in subsections 5.3(a) through 5.3(g), inclusive,
hereof.

                                   ARTICLE VI
                    LIMITATION OF TRANSACTIONS; SUBORDINATION

      Section 6.1 Limitation of Transactions.

      So long as any Trust Preferred Securities remain outstanding, if (i) there
shall have occurred any Event of Default under the Indenture or any event of
which the Guarantor has actual knowledge that (a) with the giving of notice or
the lapse of time or both, would constitute an Event of Default under the
Indenture and (b) in respect of which the Guarantor shall not have taken
reasonable steps to cure, (ii) there shall be a Guarantee Event of Default or
(iii) the Guarantor shall have given notice of its election of an Extension
Period as provided in the certificate evidencing the Junior Subordinated Debt
Securities and shall not have rescinded such notice, or such Extension Period or
any extension thereof shall be continuing, then the Guarantor shall not, and
shall not permit any subsidiary of the Guarantor, to (x) declare or pay any
dividends or distributions on, or redeem, purchase, acquire or make a
liquidation payment with respect to, any of the Guarantor's capital stock or (y)
make any payment of principal, interest or premium, if any, on or repay,
repurchase or redeem any debt securities of the Guarantor that rank on a parity
with or junior in interest to the Junior Subordinated Debt Securities or make
any guarantee payments with respect to any guarantee by the Guarantor of the
debt securities of any subsidiary of the Guarantor if such guarantee ranks on a
parity with or junior in interest to the Junior Subordinated Debt Securities
(other than (a) dividends or distributions in common stock of the Guarantor, (b)
any declaration of a dividend in connection with the implementation of a
shareholders' rights plan, or the issuance of capital stock of any class or
series under any such plan in the future, or the redemption or repurchase of any
such rights pursuant thereto, (c) payments under this Guarantee, any other
similar guarantee by the Guarantor in respect of Trust Preferred Securities
issued by a trust holding Junior Subordinated Debt Securities issued under the
Indenture, (d) repurchases, redemptions or other acquisitions of capital stock
in connection with any of the Guarantor's benefit plans or other similar
arrangements with or for the benefit of its employees, officers, directors,
consultants or advisors, or (e) the purchase of fractional interests in shares
of the Guarantor's capital stock pursuant to the conversion or exchange
provisions of such capital stock or the security being converted or exchanged).

      Section 6.2 Ranking.

      This Guarantee will constitute an unsecured obligation of the Guarantor
and will rank (i) subordinate and junior in right of payment to all Senior
Indebtedness of the Guarantor in the same manner and to the same extent as set
forth in Article IV of the Indenture, (ii) on an equal basis with any series of
junior subordinated debt securities issued under the Indenture, and any
guarantee of the Guarantor in respect of any trust preferred securities issued
by a trust to which such debt securities are issued, and (iii) senior to all
common stock of the Guarantor.
<PAGE>

                                  ARTICLE VII
                                   TERMINATION

      Section 7.1 Termination.

      This Guarantee shall terminate upon:

            (a) full payment of the Redemption Price of all Trust Preferred
      Securities,

            (b) distribution of the Junior Subordinated Debt Securities to the
      Holders in exchange for all the outstanding Trust Preferred Securities, or

            (c) full payment of the amounts payable in accordance with the Trust
      Agreement upon liquidation of the Trust.

Notwithstanding the foregoing, this Guarantee will continue to be effective or
will be reinstated, as the case may be, if at any time any Holder must restore
payment of any sums paid under the Trust Preferred Securities or under this
Guarantee.

                                  ARTICLE VIII
                                 INDEMNIFICATION

      Section 8.1 Exculpation.

            (a) No Indemnified Person shall be liable, responsible or
      accountable in damages or otherwise to the Guarantor or any Covered Person
      for any loss, damage, liability, expense or claim incurred by reason of
      any act or omission performed or omitted by such Indemnified Person in
      good faith in accordance with this Guarantee and in a manner that such
      Indemnified Person reasonably believed to be within the scope of the
      authority conferred on such Indemnified Person by this Guarantee or by
      law, except that an Indemnified Person shall be liable for any such loss,
      damage or claim incurred by reason of such Indemnified Person's negligence
      or willful misconduct with respect to such acts or omissions.

            (b) An Indemnified Person shall be fully protected in relying in
      good faith upon the records of the Guarantor and upon such information,
      opinions, reports or statements presented to the Guarantor by any Person
      as to matters the Indemnified Person reasonably believes are within such
      other Person's professional or expert competence including information,
      opinions, reports or statements as to the value and amount of the assets,
      liabilities, profits, losses, or any other facts pertinent to the
      existence and amount of assets from which Distributions to Holders might
      properly be paid.

      Section 8.2 Compensation and Indemnity.

            (a) The Guarantor shall pay to the Guarantee Trustee from time to
      time reasonable compensation for its services. The Guarantee Trustee's

<PAGE>

      compensation shall not be limited by any law on compensation of a trustee
      of an express trust. The Guarantor shall reimburse the Guarantee Trustee
      upon request for all reasonable out-of-pocket expenses incurred by it.
      Such expenses shall include the reasonable compensation and expenses of
      the Guarantee Trustee's agents and counsel.

            (b) The Guarantor shall indemnify each of the Indemnified Persons
      (including the cost of defending itself) against any loss, liability or
      expense incurred by it except as set forth in the next paragraph in the
      performance of its duties under this Guarantee. An Indemnified Person
      shall notify the Guarantor promptly of any claim for which it may seek
      indemnity. The Guarantor shall defend the claim and the Indemnified Person
      shall cooperate in the defense. The Guarantor need not pay for any
      settlement made without its consent, which consent shall not be
      unreasonably withheld.

            (c) The Guarantor need not reimburse any expense or indemnify
      against any loss or liability incurred by an Indemnified Person through
      such Indemnified Person's negligence or bad faith.

            (d) To secure the Guarantor's payment obligations in this Section
      8.2, the Guarantee Trustee shall have a lien prior to the Trust Preferred
      Securities on all money or property held or collected by the Guarantee
      Trustee, except money or property held in trust to pay Distributions on,
      or for redemption pursuant to Sections 7.3 and 7.4 of the Trust Agreement
      of, the Trust Preferred Securities.

                                   ARTICLE IX
                                  MISCELLANEOUS

      Section 9.1 Successors and Assigns.

      All guarantees and agreements contained in this Guarantee shall bind the
successors, assigns, receivers, trustees and representatives of the Guarantor
and shall inure to the benefit of the Guarantee Trustee, any Successor Guarantee
Trustee and the Holders of the Trust Preferred Securities then outstanding.
Except in connection with a consolidation, merger, sale or conveyance involving
the Guarantor that is permitted by Article VI of the Indenture and pursuant to
which the successor or assignee agrees in writing to perform the Guarantor's
obligations hereunder, the Guarantor shall not assign its obligations hereunder.

      Section 9.2 Amendments.

      Except with respect to any changes that do not materially adversely affect
the rights of the Holders (in which case no consent of the Holders will be
required), this Guarantee may not be amended without the prior approval of the
Holders of at least a Majority in Liquidation Amount of the Trust Preferred
Securities. The provisions of Section 11.2 of the Trust Agreement with respect
to meetings of, and action by written consent of, the Holders apply to the
giving of such approval.
<PAGE>

      Section 9.3 Notices.

      Any notice or communication by the Guarantor or the Guarantee Trustee to
the other is duly given if in writing and delivered in person or mailed by
first-class mail:

(a)      if to the Guarantor:
             Omnicom Group Inc.
             437 Madison Avenue
             New York, New York  10022
             Attention:______________________________

(b)      if to the Guarantee Trustee:
             [Name of Trustee]
             [Address]
             ________________________________________
             ________________________________________
             Attention:______________________________

      The Guarantor or the Guarantee Trustee by notice to the other may
designate additional or different addresses for subsequent notices or
communications.

      Any notice or communication to a Holder shall be mailed by first-class
mail to the address shown on the books and records of the Trust. Failure to mail
a notice or communication to a Holder or any defect in it shall not affect its
sufficiency with respect to other Holders.

      If a notice or communication is mailed or published in the manner provided
above, within the time prescribed, it is duly given, whether or not the Holder
receives it.

      If the Guarantor mails a notice or communication to Holders, it shall mail
a copy to the Guarantee Trustee at the same time.

      Section 9.4 Counterparts.

      This Guarantee may be executed in any number of counterparts and by the
parties hereto in separate counterparts, each of which when so executed shall be
deemed to be an original and all of which taken together shall constitute one
and the same agreement.

      Section 9.5 Benefit.

      This Guarantee is solely for the benefit of the Holders and, subject to
Section 3.1(a), is not separately transferable from the Trust Preferred
Securities.

      Section 9.6 Governing Laws.

      THIS GUARANTEE AGREEMENT SHALL BE GOVERNED BY THE LAWS OF THE STATE OF NEW
YORK APPLICABLE TO AGREEMENTS MADE AND

<PAGE>

TO BE PERFORMED IN SUCH STATE, WITHOUT REGARD TO THE CONFLICT OF LAWS PROVISIONS
THEREOF.
<PAGE>

      IN WITNESS WHEREOF, the parties hereto have caused this Guarantee to be
duly executed as of the day and year first above written.

                                      OMNICOM GROUP INC.,
                                        as Guarantor

                                      By: ______________________________
                                      Name:
                                      Its:

Attest:
___________________________
                                      [NAME OF TRUSTEE],
                                        as Guarantee Trustee

                                      By: ______________________________
                                      Name:
                                      Its: