EXHIBIT 99.5
 
                                     
                                        ___________, 199__


                           EXCHANGE AGENT AGREEMENT
                           ------------------------


The Bank of New York
Corporate Trust Trustee Administration
101 Barclay Street - 21st Floor
New York, New York 10286

Ladies and Gentlemen:

          Aon Corporation, a Delaware corporation (the "Company"), and Aon
Capital A, a Delaware statutory business trust (the "Trust"), propose to make an
offer (the "Exchange Offer") to exchange up to $800,000,000 aggregate
liquidation amount of the Trust's 8.205% Capital Securities due January 1, 2027
(the "Old Securities"), which have been registered under the Securities Act of
1933, as amended, for a like aggregate liquidation amount of the Trust's
outstanding 8.205% Capital Securities due January 1, 2027 (the "New
Securities").  The terms and conditions of the Exchange Offer as currently
contemplated are set forth in a prospectus, dated ___________, 199__ (the
"Prospectus") and in the related Letter of Transmittal, proposed to be
distributed to all record holders of the Old Securities.  The Old Securities and
the New Securities are collectively referred to herein as the "Securities."

          The Company and the Trust hereby appoint The Bank of New York to act
as exchange agent (the "Exchange Agent") in connection with the Exchange Offer.
References hereinafter to "you" shall refer to The Bank of New York.

          The Exchange Offer is expected to be commenced by the Company and the
Trust on or about _____________, 1997.  The Letter of Transmittal accompanying
the Prospectus (or in the case of book entry securities, the ATOP system) is to
be used by the holders of the Old Securities to accept the Exchange Offer and
contains instructions with respect to the delivery of certificates for Old
Securities tendered in connection therewith.

          The Exchange Offer shall expire at 5:00 P.M., New York City time, on
_____________, 1997 or on such later date or time to which the Company and the
Trust may extend the Exchange Offer (the "Expiration Date").  Subject to the
terms and conditions set forth in the Prospectus, the Company and the Trust
expressly reserve the right to extend the Exchange Offer from time to time and
may extend the Exchange Offer by giving oral (confirmed in writing) or written
notice to you before 9:00 A.M., New York City time, on the business day
following the previously scheduled Expiration Date.

 
          The Company and the Trust expressly reserve the right to amend or
terminate the Exchange Offer, and not to accept for exchange any Old Securities
not theretofore accepted for exchange, upon the occurrence of any of the
conditions of the Exchange Offer specified in the Prospectus under the caption
"The Exchange Offer -- Conditions to the Exchange Offer."  The Company and the
Trust will give oral (confirmed in writing) or written notice of any amendment,
termination or nonacceptance to you as promptly as practicable.

          In carrying out your duties as Exchange Agent, you are to act in
accordance with the following instructions:

          1.   You will perform such duties and only such duties as are
specifically set forth in the section of the Prospectus captioned "The Exchange
Offer" or as specifically set forth herein; provided, however, that in no way
will your general duty to act in good faith be discharged by the foregoing.

          2.   You will establish an account with respect to the Old Securities
at The Depository Trust Company (the "Book-Entry Transfer Facility") for
purposes of the Exchange Offer within two business days after the date of the
Prospectus, and any financial institution that is a participant in the Book-
Entry Transfer Facility's systems may make book-entry delivery of the Old
Securities by causing the Book-Entry Transfer Facility to transfer such Old
Securities into your account in accordance with the Book-Entry Transfer
Facility's procedure for such transfer.

          3.   You are to examine each of the Letters of Transmittal and
certificates for Old Securities (or confirmation of book-entry transfer into
your account at the Book-Entry Transfer Facility) and any other documents
delivered or mailed to you by or for holders of the Old Securities, and any
book-entry confirmations (as defined in the Prospectus) received by you with
respect to Old Securities, to ascertain whether: (i) the Letters of Transmittal
and any such other documents are duly executed and properly completed in
accordance with instructions set forth therein and that such book-entry
confirmations are in due and proper form and contain the information required to
be set forth therein; (ii) the Old Securities have otherwise been properly
tendered; (iii) Old Securities are tendered in aggregate liquidation amounts of
$100,000 (100 Capital Securities) or any integral multiple of $1,000 in excess
thereof and if any Old Securities are tendered for exchange in part, the
untendered aggregate liquidation amount thereof is $100,000 (100 Capital
Securities) or any integral multiple of $1,000 in excess thereof and (iv)
holders have provided their correct Tax Identification Number or required
certification. Determination of all questions as to validity, form, eligibility
and acceptance for exchange of any Old Securities shall be made by the Company
or the Trust,  whose determination shall be final and binding.  In each case
where the Letter of Transmittal or any other document has been improperly
completed or executed or any of the certificates for Old Securities are not in
proper form for transfer or some other irregularity in connection with the
acceptance of the Exchange Offer exists, you will endeavor to inform the
presenters of the need for fulfillment of all require-

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ments and to take any other action as may be necessary or advisable to cause
such irregularity to be corrected.

          4.   With the approval of the President, Senior Vice President,
Executive Vice President, or any Vice President of the Company or an
Administrative Trustee of the Trust (such approval, if given orally, to be
confirmed in writing) or any other party designated by such an officer in
writing, you are authorized to waive any irregularities in connection with any
tender of Old Securities pursuant to the Exchange Offer.

          5.   Tenders of Old Securities may be made only as set forth in the
Letter of Transmittal and in the section of the Prospectus captioned "The
Exchange Offer," and Old Securities shall be considered properly tendered to you
only when tendered in accordance with the procedures set forth therein.

          Notwithstanding the provisions of this paragraph 5, Old Securities
which the President, Senior Vice President, Executive Vice President, or any
Vice President of the Company or an Administrative Trustee of the Trust shall
approve as having been properly ten dered shall be considered to be properly
tendered (such approval, if given orally, shall be confirmed in writing).

          6.   You shall advise the Company and the Trust with respect to any
Old Securities as soon as possible after 5:00 p.m. New York City time, on the
Expiration Date and accept their instructions with respect to disposition of
such Old Securities.

          7.   You shall accept tenders:

          (a) in cases where the Old Securities are registered in two or more
names only if signed by all named holders;

          (b) in cases where the signing person (as indicated on the Letter of
Transmittal) is acting in a fiduciary or a representative capacity only when
proper evidence of his or her authority so to act is submitted; and

          (c) from persons other than the registered holder of Old Securities
provided that customary transfer requirements, including any applicable transfer
taxes, are fulfilled.

          You shall accept partial tenders of Old Securities where so indicated
and as permitted in the Letter of Transmittal and deliver certificates for Old
Securities to the transfer agent for split-up and return any untendered Old
Securities to the holder (or such other person as may be designated in the
Letter of Transmittal) as promptly as practicable after expiration or
termination of the Exchange Offer.

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          8.  Upon satisfaction or waiver of all of the conditions to the
Exchange Offer, the Company or the Trust will notify you (such notice if given
orally, to be confirmed in writing) of its acceptance, promptly after the
Expiration Date, of all Old Securities properly tendered and you, on behalf of
the Company and the Trust, will exchange such Old Securities for New Securities
and cause such Old Securities to be cancelled.  Delivery of New Securities will
be made on behalf of the Company and the Trust by you at the rate of $1,000
aggregate liquidation amount of New Securities for each $1,000 aggregate
liquidation amount of the corresponding series of Old Securities tendered
promptly after notice (such notice if given orally, to be confirmed in writing)
of acceptance of said Old Securities by the Company and the Trust; provided,
however, that in all cases, Old Securities tendered pursuant to the Exchange
Offer will be exchanged only after timely receipt by you of certificates for
such Old Securities (or confirmation of book-entry transfer into your account at
the Book-Entry Transfer Facility), a properly completed and duly executed Letter
of Transmittal (or facsimile thereof) with any required signature guarantees and
any other required documents.  You shall issue New Securities only in
denominations of $100,000 (100 Capital Securities) or any integral multiple of
$1,000 in excess thereof.

          9.   Tenders pursuant to the Exchange Offer are irrevocable, except
that, subject to the terms and upon the conditions set forth in the Prospectus
and the Letter of Transmittal, Old Securities tendered pursuant to the Exchange
Offer may be withdrawn at any time prior to the Expiration Date.

          10.  The Company and the Trust shall not be required to exchange any
Old Securities tendered if any of the conditions set forth in the Exchange Offer
are not met.  Notice of any decision by the Company and the Trust not to
exchange any Old Securities tendered shall be given (and confirmed in writing)
by the Company or the Trust to you.

          11.  If, pursuant to the Exchange Offer, the Company and the Trust do
not accept for exchange all or part of the Old Securities tendered because of an
invalid tender, the occurrence of certain other events set forth in the
Prospectus under the caption "The Exchange Offer -- Conditions to the Exchange
Offer" or otherwise, you shall as soon as practicable after the expiration or
termination of the Exchange Offer return those certificates for unaccepted Old
Securities (or effect appropriate book-entry transfer), together with any
related required documents and the Letters of Transmittal relating thereto that
are in your possession, to the persons who deposited them.

          12.  All certificates for reissued Old Securities, unaccepted Old
Securities or for New Securities shall be forwarded by (a) first-class certified
mail, return receipt requested under a blanket surety bond protecting you and
the Company and the Trust from loss or liability arising out of the non-receipt
or non-delivery of such certificates or (b) by registered mail insured
separately for the replacement value of each of such certificates.

          13.  You are not authorized to pay or offer to pay any concessions,

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commissions or solicitation fees to any broker, dealer, bank or other persons or
to engage or utilize any person to solicit tenders.

          14.  As Exchange Agent hereunder you:

          (a) shall have no duties or obligations other than those specifically
set forth herein or as may be subsequently agreed to in writing by you and the
Company and the Trust;

          (b) will be regarded as making no representations and having no
responsibilities as to the validity, sufficiency, value or genuineness of any of
the certificates or the Old Securities represented thereby deposited with you
pursuant to the Exchange Offer, and will not be required to and will make no
representation as to the validity, value or genuineness of the Exchange Offer;

          (c) shall not be obligated to take any legal action hereunder which
might in your reasonable judgment involve any expense or liability, unless you
shall have been furnished with reasonable indemnity;

          (d) may reasonably rely on and shall be protected in acting in
reliance upon any certificate, instrument, opinion, notice, letter, telegram or
other document or security delivered to you and reasonably believed by you to be
genuine and to have been signed by the proper party or parties;

          (e) may reasonably act upon any tender, statement, request, comment,
agreement or other instrument whatsoever not only as to its due execution and
validity and effectiveness of its provisions, but also as to the truth and
accuracy of any information contained therein, which you shall in good faith
believe to be genuine or to have been signed or represented by a proper person
or persons;

          (f) may rely on and shall be protected in acting upon written or oral
instructions from any officer of the Company and the Trust;

          (g) may consult with your counsel with respect to any questions
relating to your duties and responsibilities and the advice or opinion of such
counsel shall be full and complete authorization and protection in respect of
any action taken, suffered or omitted to be taken by you hereunder in good faith
and in accordance with the advice or opinion of such counsel; and

          (h) shall not advise any person tendering Old Securities pursuant to
the Exchange Offer as to the wisdom of making such tender or as to the market
value or decline or appreciation in market value of any Old Securities.

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          15.  You shall take such action as may from time to time be requested
by the Company or the Trust or their respective counsel (and such other action
as you may reasonably deem appropriate) to furnish copies of the Prospectus,
Letter of Transmittal and the Notice of Guaranteed Delivery (as defined in the
Prospectus) or such other forms as may be approved from time to time by the
Company and the Trust, to all persons requesting such documents and to accept
and comply with telephone requests for information relating to the Exchange
Offer, provided that such information shall relate only to the procedures for
accepting (or withdrawing from) the Exchange Offer.  The Company or the Trust
will furnish you with copies of such documents at your request.  All other
requests for information relating to the Exchange Offer shall be directed to the
Company and the Trust, Attention: ____________________.

          16.  You shall advise by facsimile transmission or telephone, and
promptly thereafter confirm in writing to _____________________________ of the
Company and the Trust and such other person or persons as it may request, daily
(and more frequently during the week immediately preceding the Expiration Date
and if otherwise requested) up to and including the Expiration Date, as to the
number of Old Securities which have been tendered pursuant to the Exchange Offer
and the items received by you pursuant to this Agreement, separately report ing
and giving cumulative totals as to items properly received and items improperly
received. In addition, you will also inform, and cooperate in making available
to, the Company and the Trust or any such other person or persons upon oral
request made from time to time prior to the Expiration Date of such other
information as it or he or she reasonably requests.  Such coopera tion shall
include, without limitation, the granting by you to the Company and the Trust
and such person as the Company and the Trust may request of access to those
persons on your staff who are responsible for receiving tenders, in order to
ensure that immediately prior to the Expiration Date the Company and the Trust
shall have received information in sufficient detail to enable it to decide
whether to extend the Exchange Offer.  You shall prepare a final list of all
persons whose tenders were accepted, the aggregate liquidation amount of Old
Securities tendered, the aggregate liquidation amount of Old Securities accepted
and deliver said list to the Company and the Trust.

          17.  Letters of Transmittal, book-entry confirmations  and Notices of
Guaranteed Delivery shall be stamped by you as to the date and the time of
receipt thereof and shall be preserved by you for a period of time at least
equal to the period of time you preserve other records pertaining to the
transfer of securities, or one year, whichever is longer, and thereafter shall
be delivered by you to the Company and the Trust.  You shall dispose of unused
Letters of Transmittal and other surplus materials by returning them to the
Company or the Trust.

          18.  You hereby expressly waive any lien, encumbrance or right of set-
off whatsoever that you may have with respect to funds deposited with you for
the payment of trans fer taxes by reasons of amounts, if any, borrowed by the
Company or the Trust, or any of its subsidiaries or affiliates pursuant to any
loan or credit agreement with you or for compensation owed to you hereunder or
for any other matter.

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          19.  For services rendered as Exchange Agent hereunder, you shall be
entitled to such compensation as set forth on Schedule I attached hereto.

          20.  You hereby acknowledge receipt of the Prospectus and the Letter
of Transmittal and further acknowledge that you have examined each of them.  Any
inconsistency between this Agreement, on the one hand, and the Prospectus and
the Letter of Transmittal (as they may be amended from time to time), on the
other hand, shall be resolved in favor of the latter two documents, except with
respect to the duties, liabilities and indemnification of you as Exchange Agent,
which shall be controlled by this Agreement.

          21.  The Company and the Trust covenant and agree to indemnify and
hold you harmless in your capacity as Exchange Agent hereunder against any loss,
liability, cost or expense, including reasonable attorneys' fees and expenses,
arising out of or in connection with any act, omission, delay or refusal made by
you in reliance upon any signature, endorsement, assignment, certificate, order,
request, notice, instruction or other instrument or document reasonably believed
by you to be valid, genuine and sufficient and in accepting any tender or
effecting any transfer of Old Securities reasonably believed by you in good
faith to be authorized, and in delaying or refusing in good faith to accept any
tenders or effect any transfer of Old Securities; provided, however, that the
Company and the Trust shall not be liable for indemnification or otherwise for
any loss, liability, cost or expense to the extent arising out of your bad
faith, gross negligence or willful misconduct.  In no case shall the Company and
the Trust be liable under this indemnity with respect to any claim against you
unless the Company and the Trust shall be notified by you, by letter or cable or
by facsimile confirmed by letter, of the written assertion of a claim against
you or of any other action commenced against you, promptly after you shall have
received any such written assertion or notice of commencement of action.  The
Company and the Trust shall be entitled to participate at their own expense in
the defense of any such claim or other action, and, if the Company and the Trust
so elect, the Company or the Trust may assume the defense of any pending or
threatened action against you in respect of which indemnification may be sought
hereunder with counsel reasonably acceptable to you, in which case the Company
or the Trust, as applicable, shall not thereafter be liable under this paragraph
for the fees and disbursements of legal counsel retained by you; provided that
the Company and the Trust shall not be entitled to assume the defense of any
such action if the named parties to such action include the Company or the Trust
and you and representation of the parties by the same legal counsel would, in
your opinion, be inappropriate due to actual or potential conflicting interests
between them.  It is understood that neither the Company nor the Trust shall be
liable under this paragraph for the fees and disbursements of more than one
legal counsel for you.  In the event that the Company or the Trust shall assume
the defense of any such suit with counsel reasonably acceptable to you, the
Company or the Trust, as applicable, shall not therewith be liable for the fees
and expenses of any counsel retained by you.

          Without the prior written consent of the Company and the Trust, you
will not settle, compromise or consent to the entry of any judgment in any
pending or threatened claim,

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action or proceeding in respect of which indemnification could be sought in
accordance with the indemnification provisions of this Agreement (whether or not
you, the Company or the Trust or any of their directors, officers and
controlling persons is an actual or potential party to such claim, action or
proceeding), unless such settlement or consent includes an unconditional release
of the Company and the Trust and their directors, officers and controlling
persons from all liability arising out of such claim, action or proceeding.

          22.  You shall arrange to comply with all requirements under the tax
laws of the United States, including those relating to missing Tax
Identification Numbers, and shall file any appropriate reports with the Internal
Revenue Service.  The Company and the Trust understand that you are required to
deduct 31% on payments to holders who have not supplied their correct Taxpayer
Identification Number or required certification.  Such funds will be turned over
to the Internal Revenue Service in accordance with applicable regulations.

          23.  You shall deliver or cause to be delivered, in a timely manner to
each governmental authority to which any transfer taxes are payable in respect
of the exchange of Old Securities, your check in the amount of all transfer
taxes so payable, and the Company and the Trust shall reimburse you for the
amount of any and all transfer taxes payable in respect of the exchange of Old
Securities; provided, however, that you shall reimburse the Company or the Trust
for amounts refunded to you in respect of your payment of any such transfer
taxes, at such time as such refund is received by you.

          24.  This Agreement and your appointment as Exchange Agent hereunder
shall be construed and enforced in accordance with the laws of the State of New
York applicable to agreements made and to be performed entirely within such
state, and without regard to conflicts of law principles.

          25.  Nothing in this Agreement, express or implied, is intended to or
shall confer upon any other person any right, benefit or remedy of any nature
whatsoever under or by reason of this Agreement.  Without limiting the
foregoing, the parties hereto expressly agree that no holder of Old Securities
or New Securities shall have any right, benefit or remedy of any nature
whatsoever under or by reason of this Agreement.

          26.  This Agreement may be executed in two or more counterparts, each
of which shall be deemed to be an original and all of which taken together shall
constitute one and the same agreement.

          27.  In case any provision of this Agreement shall be invalid, illegal
or unenforceable, the validity, legality and enforceability of the remaining
provisions shall not in any way be affected or impaired thereby.

          28.  This Agreement shall not be deemed or construed to be modified,
amended, rescinded, cancelled or waived, in whole or in part, except by a
written instrument

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signed by a duly authorized representative of the party to be charged.  This
Agreement may not be modified orally.

          29.  Unless otherwise provided herein, all notices, requests and other
communications to any party hereunder shall be in writing (including facsimile
or similar writing) and shall be given to such party, addressed to it, at its
address or telecopy number set forth below:


          If to the Company or the Trust:

               ___________________________
               ___________________________
               ___________________________

               Facsimile: ________________
               Attention: ________________


          If to the Exchange Agent:

               The Bank of New York
               101 Barclay Street
               Floor 21 West
               New York, New York  10286

               Facsimile:  (212) 815-5915
               Attention:  Corporate Trust Trustee
                                Administration
 

          30.  Unless terminated earlier by the parties hereto, this Agreement
shall terminate 90 days following the Expiration Date.  Notwithstanding the
foregoing, Paragraphs 19, 21 and 23 shall survive the termination of this
Agreement.  Upon any termination of this Agreement, you shall promptly deliver
to the Company or the Trust any certificates for Securities, funds or property
then held by you as Exchange Agent under this Agreement.

          31.  This Agreement shall be binding and effective as of the date
hereof.

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          Please acknowledge receipt of this Agreement and confirm the
arrangements herein provided by signing and returning the enclosed copy.



                                       AON CORPORATION



                                       By:_____________________________
                                          Name:
                                          Title:


                                       AON CAPITAL A



                                       By:_____________________________
                                          Name:
                                          Title: Administrative Trustee


Accepted as of the date
first above written:

THE BANK OF NEW YORK,
as Exchange Agent


By:_____________________
   Name:
   Title:

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                                   SCHEDULE I

                                      FEES


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