SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM 10-Q

      X          QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d)
      -            OF THE SECURITIES AND EXCHANGE ACT OF 1934

                  FOR THE QUARTERLY PERIOD ENDED JUNE 30, 2001

                                       OR

                TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d)
      -              OF THE SECURITIES EXCHANGE ACT OF 1934

                          Commission file number 1-7933

                                 Aon Corporation
                                 ---------------
             (Exact Name of Registrant as Specified in its Charter)

           DELAWARE                                          36-3051915
           --------                                          ----------
(State or Other Jurisdiction of                             (IRS Employer
Incorporation or Organization)                              Identification No.)



200 E. RANDOLPH ST., CHICAGO, ILLINOIS                       60601
- --------------------------------------                       -----
(Address of Principal Executive Offices)                    (Zip Code)

           (312) 381-1000
           --------------
   (Registrant's Telephone Number)


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  and Exchange Act
of 1934  during the  preceding  3 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
                                              ---     ---

Number of shares of common stock outstanding:

                                                 No. Outstanding
               Class                              as of 6-30-01
               -----                              -------------

       $1.00 par value Common                      266,485,865




                                               PART 1
                                        Financial Information
                                           Aon CORPORATION
                       Condensed Consolidated Statements of Financial Position

 (millions)                                                          AS OF             AS OF
                                                                JUNE 30, 2001      DEC. 31, 2000
                                                                ---------------------------------
 ASSETS                                                           (Unaudited)

                                                                                  
 Investments

   Fixed maturities at fair value                                    $   2,252         $   2,337

   Equity securities at fair value                                         529               492

   Short-term investments                                                2,414             2,325

   Other investments                                                       769               865

                                                                ---------------   ---------------
       TOTAL INVESTMENTS                                                 5,964             6,019


 CASH                                                                      765             1,118


 RECEIVABLES

   Insurance brokerage and consulting
        services                                                         7,227             6,952

   Premiums and other                                                    1,246             1,278

                                                                ---------------   ---------------
       TOTAL RECEIVABLES                                                 8,473             8,230


 EXCESS OF COST OVER NET ASSETS PURCHASED                                3,449             3,427


 OTHER INTANGIBLE ASSETS                                                   481               489


 OTHER ASSETS                                                            3,334             2,968


                                                                ---------------   ---------------
       TOTAL ASSETS                                                  $  22,466         $  22,251
                                                                ===============   ===============



                                                                     AS OF             AS OF
                                                                JUNE 30, 2001      DEC. 31, 2000
                                                                ---------------------------------
 LIABILITIES AND STOCKHOLDERS' EQUITY                             (Unaudited)

 INSURANCE PREMIUMS PAYABLE                                          $   8,643         $   8,212

 POLICY LIABILITIES
   Future policy benefits                                                1,064             1,054
   Policy and contract claims                                              911               801
   Unearned and advance premiums                                         1,947             1,935
   Other policyholder funds                                                942             1,069
                                                                ---------------   ---------------
       TOTAL POLICY LIABILITIES                                          4,864             4,859

 GENERAL LIABILITIES
   General expenses                                                      1,684             1,619
   Short-term borrowings                                                   204               309
   Notes payable                                                         1,746             1,798
   Other liabilities                                                     1,005             1,216
                                                                ---------------   ---------------
       TOTAL LIABILITIES                                                18,146            18,013


 COMMITMENTS AND CONTINGENT LIABILITIES

 REDEEMABLE PREFERRED STOCK                                                 50                50

 COMPANY-OBLIGATED MANDATORILY REDEEMABLE
   PREFERRED CAPITAL SECURITIES OF SUBSIDIARY
   TRUST HOLDING SOLELY THE COMPANY'S JUNIOR
   SUBORDINATED DEBENTURES                                                 800               800


 STOCKHOLDERS' EQUITY
   Common stock - $1 par value                                             268               264
   Paid-in additional capital                                              799               706
   Accumulated other comprehensive loss                                   (413)             (377)
   Retained earnings                                                     3,056             3,127
   Less - Treasury stock at cost                                           (42)             (118)
          Deferred compensation                                           (198)             (214)
                                                                ---------------   ---------------
       TOTAL STOCKHOLDERS' EQUITY                                        3,470             3,388

                                                                ---------------   ---------------
       TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY                    $  22,466         $  22,251
                                                                ===============   ===============


 See the accompanying notes to the condensed consolidated financial statements.

                                       - 2 -



                                                     AON CORPORATION
                                       Condensed Consolidated Statements of Income
                                                       (Unaudited)

                                                                         SECOND QUARTER ENDED              SIX MONTHS ENDED
                                                                   -------------------------------- -------------------------------
 (millions except per share data)                                   JUNE 30, 2001    JUNE 30, 2000   JUNE 30, 2001   JUNE 30, 2000
                                                                   ---------------  --------------- --------------- ---------------

                                                                                                               
 REVENUE
    Brokerage commissions and fees ..............................         $ 1,347          $ 1,203         $ 2,628         $ 2,408
    Premiums and other ..........................................             492              491           1,000             959
    Investment income ...........................................              78              125             100             262
                                                                   ---------------  --------------- --------------- ---------------
       TOTAL REVENUE ............................................           1,917            1,819           3,728           3,629
                                                                   ---------------  --------------- --------------- ---------------

 EXPENSES
    General expenses ............................................           1,523            1,262           2,919           2,533
    Benefits to policyholders ...................................             260              257             552             509
    Interest expense ............................................              31               33              67              64
    Amortization of intangible assets ...........................              39               39              78              77
                                                                   ---------------  --------------- --------------- ---------------
       TOTAL EXPENSES ...........................................           1,853            1,591           3,616           3,183
                                                                   ---------------  --------------- --------------- ---------------

 INCOME BEFORE INCOME TAX, MINORITY INTEREST AND ACCOUNTING CHANGE             64              228             112             446
    Provision for income tax ....................................              25               89              44             174
                                                                   ---------------  --------------- --------------- ---------------
 INCOME BEFORE MINORITY INTEREST AND ACCOUNTING CHANGE ..........              39              139              68             272
    Minority interest - 8.205% trust preferred capital securities             (10)             (10)            (20)            (20)
                                                                   ---------------  --------------- --------------- ---------------
 INCOME BEFORE ACCOUNTING CHANGE ................................              29              129              48             252
    Cumulative effect of change in accounting principle, net of tax             -                -               -              (7)
                                                                   ---------------  --------------- --------------- ---------------
 NET INCOME .....................................................         $    29          $   129         $    48         $   245
                                                                   ===============  =============== =============== ===============
    Preferred stock dividends ...................................               -                -              (1)             (1)
                                                                   ---------------  --------------- --------------- ---------------
 NET INCOME AVAILABLE FOR COMMON STOCKHOLDERS ...................         $    29          $   129         $    47         $   244
                                                                   ===============  =============== =============== ===============

 BASIC NET INCOME PER SHARE:
    Before accounting change ....................................         $  0.11          $  0.50         $  0.18         $  0.97
    Cumulative effect of change in accounting principle .........               -                -               -           (0.03)
                                                                   ---------------  --------------- --------------- ---------------
                Basic net income per share ......................         $  0.11          $  0.50         $  0.18         $  0.94
                                                                   ===============  =============== =============== ===============

 DILUTIVE NET INCOME PER SHARE:
    Before accounting change ....................................         $  0.11          $  0.49         $  0.17         $  0.96
    Cumulative effect of change in accounting principle .........               -                -               -           (0.03)
                                                                   ---------------  --------------- --------------- ---------------
                Dilutive net income per share ...................         $  0.11          $  0.49         $  0.17         $  0.93
                                                                   ===============  =============== =============== ===============

 CASH DIVIDENDS PER SHARE PAID ON COMMON STOCK ..................         $ 0.225          $  0.22         $ 0.445         $  0.43
                                                                   ===============  =============== =============== ===============

 Dilutive average common and common equivalent shares outstanding           270.2            261.7           268.7           261.1
                                                                   ===============  =============== =============== ===============


See the accompanying notes to the condensed consolidated financial statements.

                                       - 3 -



                                                    AON CORPORATION
                                 CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
                                                      (UNAUDITED)

                                                                                                    SIX MONTHS ENDED
                                                                                             -------------------------------
                                                                                                JUNE 30,         JUNE 30,
 (millions)                                                                                       2001             2000
                                                                                             --------------    -------------

                                                                                                                
 CASH FLOWS FROM OPERATING ACTIVITIES:
   Net income ...........................................................................           $   48           $  245
   Adjustments to reconcile net income to cash provided by operating activities
        Cumulative effect of change in accounting principle, net of tax .................                -                7
        Insurance operating assets and liabilities net of reinsurance ...................              (45)              18
        Amortization of intangible assets ...............................................               78               77
        Depreciation and amortization of property, equipment and software ...............               90               88
        Income taxes ....................................................................              (87)              62
        Special charge and purchase accounting liabilities ..............................              114              (73)
        Valuation changes on investments, income on disposals and impairments ...........               96              (48)
        Other receivables and liabilities - net .........................................                2             (114)
                                                                                             --------------    -------------
            CASH PROVIDED BY OPERATING ACTIVITIES .......................................              296              262
                                                                                             --------------    -------------

 CASH FLOWS FROM INVESTING ACTIVITIES:
   Sale of investments
        Fixed maturities
            Maturities ..................................................................               58               42
            Calls and prepayments .......................................................               47               80
            Sales .......................................................................              605              170
        Equity securities ...............................................................              158               83
        Other investments ...............................................................               27              183
   Purchase of investments
        Fixed maturities ................................................................             (630)            (245)
        Equity securities ...............................................................             (146)             (41)
        Other investments ...............................................................              (53)            (260)
   Sale / (purchase) of short-term investments - net ....................................             (162)              (2)
   Acquisition of subsidiaries ..........................................................              (70)             (41)
   Property and equipment and other - net ...............................................             (112)             (73)
                                                                                             --------------    -------------
            CASH USED IN INVESTING ACTIVITIES ...........................................             (278)            (104)
                                                                                             --------------    -------------

 CASH FLOWS FROM FINANCING ACTIVITIES:
    Treasury stock transactions - net ...................................................               19              (63)
    Issuance (payments) of short-term borrowings - net ..................................             (105)             101
    Issuance of long-term debt ..........................................................                -              250
    Repayment of long-term debt .........................................................              (33)             (31)
    Interest sensitive, annuity and investment-type contracts
        Deposits ........................................................................                5               35
        Withdrawals .....................................................................             (134)            (239)
    Cash dividends to stockholders ......................................................             (118)            (111)
                                                                                             --------------    -------------
            CASH USED IN FINANCING ACTIVITIES ...........................................             (366)             (58)
                                                                                             --------------    -------------

 EFFECT OF EXCHANGE RATE CHANGES ON CASH ................................................               (5)              (7)
                                                                                             --------------    -------------
 INCREASE (DECREASE) IN CASH ............................................................             (353)              93
 CASH AT BEGINNING OF PERIOD ............................................................            1,118              837
                                                                                             --------------    -------------
 CASH AT END OF PERIOD ..................................................................           $  765           $  930
                                                                                             ==============    =============


See the accompanying notes to condensed consolidated financial statements.

                                       - 4 -


NOTES TO THE CONDENSED CONSOLIDATED FINANCIAL STATEMENTS


1.       Statement of Accounting Principles
         ----------------------------------

         The financial  results included in this report are stated in conformity
         with accounting  principles generally accepted in the United States and
         are unaudited but include all normal  recurring  adjustments  which the
         Registrant  ("Aon") considers  necessary for a fair presentation of the
         results for such  periods.  These interim  figures are not  necessarily
         indicative of results for a full year as further discussed below.

         Refer to the consolidated  financial statements and notes in the Annual
         Report  to  Stockholders  for the  year  ended  December  31,  2000 for
         additional  details  of  Aon's  financial   position,   as  well  as  a
         description  of the  accounting  policies  which  have  been  continued
         without  material  change.  The details  included in the notes have not
         changed  except as a result of normal  transactions  in the interim and
         the events mentioned in the footnotes below.


2.       Accounting and Disclosure Changes
         ---------------------------------

         In December 1999, the Securities and Exchange  Commission  (SEC) issued
         Staff  Accounting  Bulletin (SAB) No. 101, which provides  guidance for
         applying  generally  accepted  accounting  principles  relating  to the
         timing of revenue  recognition in financial  statements  filed with the
         SEC.  Effective  January 1, 2000, in accordance  with the provisions of
         SAB 101, Aon established a provision for estimated returned commissions
         from policy  cancellations.  In 1999 and previous years, Aon recognized
         returned commissions when they occurred.  The cumulative effect of this
         accounting  change was an  after-tax  charge of $7 million or $0.03 per
         share in the first quarter of 2000.

         In September  2000,  the Financial  Accounting  Standards  Board (FASB)
         issued  Statement  No. 140,  Accounting  for Transfers and Servicing of
         Financial Assets and Extinguishments of Liabilities.  Statement No. 140
         replaces Statement No. 125 and revises the standards for accounting for
         securitizations  and other transfers of financial assets and collateral
         and requires  certain  disclosures.  Statement No. 140 became effective
         for all transfers of financial  assets  occurring after March 31, 2001.
         Implementation  of Statement No. 140 did not have a material  impact on
         the consolidated financial statements.

         In June 2001,  the FASB  approved the  issuance of  Statement  No. 142,
         Goodwill and Other  Intangible  Assets.  Statement  No. 142  supercedes
         Accounting  Principles  Board  Opinion  No. 17.  Under this  statement,
         goodwill and indefinite lived intangible assets are no longer amortized
         but are reviewed annually,  or more frequently if impairment indicators
         arise,  for impairment.  Separable  intangible  assets that have finite
         lives will  continue  to be  amortized  over their  useful  lives.  The
         amortization  provisions  of  Statement  No. 142 apply to goodwill  and
         intangible  assets  acquired  after  June 30,  2001.  With  respect  to
         goodwill  and  intangible  assets  acquired  prior  to  July  1,  2001,
         amortization will be discontinued  effective as of January 1, 2002. The
         full  impact  of  applying  this  statement  is yet  to be  determined.
         However, reported earnings for Aon are expected to increase by at least
         $0.36 per share on an annualized basis beginning in 2002.

                                       - 5 -


3.       Spin-Off of Underwriting Business
         ---------------------------------

         On April 20, 2001, Aon's Board of Directors approved,  in principle,  a
         plan    to  spin-off  its   underwriting   business   to  Aon's  common
         stockholders, creating two independent,  publicly-traded companies. The
         spin-off  would take the form of a  tax-free  stock  dividend  to Aon's
         common stockholders, pending a favorable Internal Revenue Service (IRS)
         ruling. The transaction is subject to final Board approval, a favorable
         IRS ruling, and certain insurance regulatory approvals.



4.       Comprehensive Income
         --------------------

         The  components of  comprehensive  income,  net of related tax, for the
         second  quarter  and six  months  ended  June 30,  2001 and 2000 are as
         follows:



                                                        Second Quarter Ended                  Six Months Ended
                                                        --------------------                  ----------------
        (millions)                                June 30, 2001    June 30, 2000       June 30, 2001    June 30, 2000
                                                  -------------    -------------       -------------    -------------

                                                                                                
        Net income                                $       29       $     129           $       48        $     245
        Net derivative losses                              -               -                  (12)               -
        Net unrealized investment gains (losses)           3              (8)                  22               (5)
        Net foreign exchange losses                       (3)            (48)                 (46)             (80)
                                                 -------------    -------------        -------------    -------------
        Comprehensive income                      $       29       $      73           $       12        $     160
                                                 =============    =============        =============    =============



         The components of accumulated other  comprehensive loss, net of related
         tax, at June 30, 2001 and December 31, 2000, are as follows:



        (millions)                                            June 30, 2001     December 31, 2000
                                                              -------------     -----------------

                                                                           
        Net derivative gains (losses)                           $       (6)       $          6
        Net unrealized investment losses                               (50)                (72)
        Net foreign exchange losses                                   (313)               (267)
        Net additional minimum pension liability                       (44)                (44)
                                                                -----------       -------------
        Accumulated other comprehensive loss                    $     (413)       $       (377)
                                                                ===========       =============



5.       Business Segments
         -----------------

         Aon classifies its businesses  into three  operating  segments based on
         the types of services and/or products delivered. There is also a fourth
         non-operating segment, Corporate and Other. The Insurance Brokerage and
         Other Services segment consists primarily of Aon's retail,  reinsurance
         and  wholesale  brokerage  operations,  as  well  as  managing  general
         underwriting,   actuarial,  loss  control,  claims,   alternative  risk
         transfer and premium  financing  services.  Certain service  businesses
         related to insurance underwriting operations are also reflected in this
         segment.  The  Consulting  segment is Aon's  human  capital  consulting
         organization  which utilizes four practice groups:  employee  benefits,
         compensation,    management   consulting   and   employment   practices
         outsourcing.  The Insurance

                                       - 6 -

         Underwriting  segment  is  comprised of  accident and health  and  life
         coverages and extended  warranty  and  specialty  property and casualty
         insurance  products.  Corporate  and  Other  segment  revenues  consist
         primarily of investment income from equity investments that  are assets
         of the underwriting  subsidiaries.  Revenues are derived from valuation
         changes in limited partnerships, investment income from  certain  other
         investments (which  include  non-income producing equities) and  income
         and losses  on  disposals of all securities, including those pertaining
         to assets maintained by the operating  segments.   Corporate  and Other
         expenses  include   general   expenses,   administrative   and  certain
         information   technology   costs,   interest   expense   and   goodwill
         amortization.

         Amounts reported in the tables for the four segments,  when aggregated,
         total  to  the  amounts  in  the  accompanying  condensed  consolidated
         financial statements. Revenues are attributed to geographic areas based
         on the location of the resources  producing the revenues.  There are no
         material inter-segment amounts to be eliminated.

         Selected information reflecting Aon's operating segments follows.



Second Quarter ended June 30:                    Insurance Brokerage                                            Insurance
(millions)                                       and Other Services                 Consulting                 Underwriting
                                                 -------------------                ----------                 ------------
                                                   2001           2000             2001         2000            2001      2000
                                                   ----           ----             ----         ----            ----      ----

                                                                                                      
Revenue
   United States                              $    602        $    545         $   157     $    109        $   393      $   394
   United Kingdom                                  238             238              37           40             70           81
   Continent of Europe                             161             143              16           14             33           28
   Rest of World                                   153             139              19           17             52           49
- ------------------------------------------- --------------- -------------- -- ------------ ----------- -- ------------ -----------
Total revenue                                 $  1,154        $  1,065         $   229     $    180        $   548      $   552
- ------------------------------------------- --------------- -------------- -- ------------ ----------- -- ------------ -----------

Income before income taxes
    excluding special charges                 $    195        $    182         $    30     $     23        $    79      $    79
Special charges                                    117               -               6            -             23            -
- ------------------------------------------- --------------- -------------- -- ------------ ----------- -- ------------ -----------
Income before income taxes                    $     78        $    182         $    24     $     23        $    56      $    79
- ------------------------------------------- --------------- -------------- -- ------------ ----------- -- ------------ -----------





Six Months ended June 30:                        Insurance Brokerage                                             Insurance
(millions)                                       and Other Services                 Consulting                 Underwriting
                                                 ------------------                 ----------                 ------------
                                                  2001           2000             2001         2000           2001         2000
                                                  ----           ----             ----         ----           ----         ----

                                                                                                     
Revenue
   United States                              $   1,143      $   1,069        $   292      $  208          $   799     $    770
   United Kingdom                                   443            442             73          79              150          159
   Continent of Europe                              401            369             38          36               61           54
   Rest of World                                    284            259             38          33              105           99
- ------------------------------------------- --------------- -------------- -- ------------ ----------- -- ------------ -----------
Total revenue                                 $   2,271      $   2,139        $   441      $  356          $ 1,115     $  1,082
- ------------------------------------------- --------------- -------------- -- ------------ ----------- -- ------------ -----------

Income before income taxes
    excluding special charges                 $     391      $    362         $    55      $   42          $   147     $    146
Special charges                                     187             -               7           -               24            -
- ------------------------------------------- --------------- -------------- -- ------------ ----------- -- ------------ -----------
Income before income taxes                    $     204      $    362         $    48      $   42          $   123     $    146
- ------------------------------------------- --------------- -------------- -- ------------ ----------- -- ------------ -----------


                                       - 7 -

Selected information for Aon's non-operating segment follows:



Corporate and Other                                   Second Quarter ended June 30,      Six Months ended June 30,
                                                      -----------------------------    ----------------------------
(millions)                                                  2001          2000               2001           2000
- ----------------------------------------------------- ------------- ---------------    --------------- ------------

                                                                                                  
Corporate and other revenue:
Change in valuation of private limited
    partnership investments                            $    (7)       $     32           $    (63)     $      60
Income from marketable equity securities
     and other investments                                   3               1                  4              4
                                                      ------------- ---------------    --------------- ------------
Corporate and other revenue before loss
     on disposals and related expenses                      (4)             33                (59)            64
Gain (loss) on disposals and related
     expenses*                                             (10)            (11)               (40)           (12)
- ----------------------------------------------------- ------------- ---------------    --------------- ------------
Corporate and other revenue                            $   (14)       $     22           $    (99)     $      52
- ----------------------------------------------------- ------------- ---------------    --------------- ------------

Non-operating expenses:
   Amortization of goodwill                            $    29        $     29           $     58      $      56
   Interest expense                                         31              33                 67             64
   General expenses                                         20              16                 39             36
- ----------------------------------------------------- ------------- ---------------    --------------- ------------
Loss before income taxes                               $   (94)       $    (56)          $   (263)     $    (104)
- ----------------------------------------------------- ------------- ---------------    --------------- ------------
<FN>
* Six months 2001 includes impairment write-downs of $29 million.
</FN>



6.       Capital Stock
         -------------

         During the first six months of 2001, Aon reissued  2,216,600  shares of
         common  stock from  treasury  for  employee  benefit  plans and 331,500
         shares  in  connection  with the  employee  stock  purchase  plan.  Aon
         acquired  114,900  shares of its common  stock at a total value of $3.9
         million during the first half of 2001. There were 1.3 million shares of
         common stock held in treasury at June 30, 2001.


7.       Capital Securities
         ------------------

         In 1997, Aon Capital A, a subsidiary  trust of Aon, issued $800 million
         of 8.205% mandatorily  redeemable preferred capital securities (capital
         securities).  The sole asset of Aon Capital A is $824 million aggregate
         principal  amount  of  Aon's  8.205%  Junior  Subordinated   Deferrable
         Interest Debentures due January 1, 2027.


8.       Business Combinations
         ---------------------

         For the second  quarter and six months of 2001, Aon made payments of $4
         million  and $8 million,  respectively,  on  restructuring  charges and
         purchase accounting liabilities relating to business combinations.

         In 1996 and 1997, Aon recorded  pretax  special  charges of $60 million
         and $145 million, respectively, related to management's commitment to a
         formal plan of restructuring Aon's brokerage operations as

                                       - 8 -

         a  result  of the acquisition of Alexander &  Alexander Services,  Inc.
         (A&A). Also in 1997, following management's commitment to a formal plan
         of  restructuring  the  A&A  and  Bain  Hogg brokerage operations,  Aon
         recorded  $264  million  in  costs  to restructure  those acquisitions.
         These  charges  primarily  related  to  termination  benefits  of  $152
         million, lease abandonments and other exit costs of $280  million,  and
         asset  impairments  of  $37  million.  As  of December  31,  2000,  all
         termination benefits have been paid.  The remaining  liability  of  $70
         million is for lease abandonments that will be paid through 2009.

         The following table  demonstrates  recent activity  regarding the lease
         abandonments and other exit costs associated with the A&A and Bain Hogg
         acquisitions:



             (millions)                            Lease Abandonments and Other
                                                             Exit Costs
                                                  -----------------------------
                                                   
             Balance at December 31, 1998                    $    155
             Cash payments in 1999 and 2000                       (77)
             Charge to expense in 1999 and 2000                     6
             Cash payments in 2001                                 (6)
             Foreign currency revaluation                          (8)
                                                           -------------
             Balance at June 30, 2001                        $     70
                                                           =============



         The combination of 1998  acquisitions  and the finalization of purchase
         accounting  for the 1997 Jauch & Hubener  acquisition  resulted  in $70
         million of purchase accounting  liabilities.  In 1999, a charge of $120
         million was recorded for a plan to  restructure  Aon's  operations as a
         result  of  business  combination  activity.  These  charges  primarily
         related to termination  benefits of $107 million,  the related  pension
         expense of $32 million,  lease abandonments and other exit costs of $41
         million,  and asset  impairments  of $10  million.  As of June 30, 2001
         these  liabilities  have been  reduced to  termination  benefits  of $3
         million and lease  abandonments  and other costs to exit an activity of
         $3 million.

         All of Aon's unpaid liabilities  relating to acquisitions are reflected
         in general expense liabilities in the condensed consolidated statements
         of financial position.


9.       Business Transformation Plan
         ----------------------------

         In fourth quarter 2000, Aon commenced a business  transformation  plan.
         This plan has been  implemented  during the fourth  quarter of 2000 and
         the  first  half of 2001 and will  continue  throughout  2001 and 2002.
         Pretax  special  charges of $82  million,  $72 million and $146 million
         were recorded in fourth quarter 2000, and the first and second quarters
         of 2001,  respectively,  and are  recorded  in general  expenses in the
         condensed  consolidated  statements  of  income.  The  charge in second
         quarter 2001  included  costs  related to  termination  benefits of $85
         million,  other  costs to exit an  activity  of $18  million  and other
         charges of $43 million, primarily relating to costs for the abandonment
         of systems and  equipment.  For the six months 2001,  charges  included
         costs related to termination  benefits of $108 million,  other costs to
         exit an  activity  of $21  million  and other  charges  of $89  million
         primarily  relating  to  costs  for  the  abandonment  of  systems  and
         equipment as well as to end Aon's involvement in certain joint ventures
         and  service  partner  relationships  that did not  meet  profitability
         hurdles.

         Since the beginning of the plan in the fourth  quarter of 2000,  nearly
         4,000  employees  have been notified that their  positions have been or
         will be  eliminated.  Over  half of those  have  already  departed

                                       - 9 -

         Aon.  Most of these positions were related to the  Insurance  Brokerage
         and Other Services segment in the U.S. and the U.K.

         For the second  quarter and first six months of 2001, Aon made payments
         of $27 million and $49 million,  respectively,  related to the business
         transformation plan.

         The following  demonstrates  the activity  related to the liability for
         termination  benefits  and  other  costs to exit an  activity  for  the
         business transformation plan.



                                                                           Other Costs
                                                        Termination         to Exit an
           (millions)                                      Benefits           Activity          Total
           --------------------------------------------------------------------------------------------

                                                                                    
           Expense charged in 2000                       $     54           $      6         $     60
           Cash payments in 2000                              (13)                (3)             (16)
           Expense charged in 2001                            108                 21              129
           Cash payments in 2001                              (37)               (12)             (49)
           --------------------------------------------------------------------------------------------
           Balance at June 30, 2001                      $    112           $     12         $    124
           --------------------------------------------------------------------------------------------


         All of Aon's unpaid liabilities relating to the business transformation
         plan are  reflected in general  expense  liabilities  in the  condensed
         consolidated statements of financial position.



10.      Income Per Share
         ----------------

         Income per share is calculated as follows:



                                                           Second Quarter ended June 30,       Six Months ended June 30,
                                                           -----------------------------       -------------------------
    (millions)                                                 2001              2000              2001         2000
    -------------------------------------------------- --------------      --------------     ------------- -----------

                                                                                                   
    Net income                                           $      29          $    129           $     48      $    245
    Redeemable preferred stock dividends                         -                 -                  1             1
                                                       --------------      --------------     ------------- -----------
    Net income for dilutive and basic                    $      29          $    129           $     47      $    244
                                                       ==============      ==============     ============= ===========

    Basic shares outstanding                                   268               259                266           259
    Common stock equivalents                                     2                 3                  3             2
                                                       --------------      --------------     ------------- -----------
    Dilutive potential common shares                           270               262                269           261
    -------------------------------------------------- --------------      --------------     ------------- -----------
    Basic net income per share                           $    0.11          $   0.50           $   0.18       $  0.94
    Dilutive net income per share                        $    0.11          $   0.49           $   0.17       $  0.93
    -------------------------------------------------- --------------      --------------     ------------- -----------



11.      Alexander & Alexander Services Inc. (A&A) Discontinued Operations
         -----------------------------------------------------------------

         A&A  discontinued  its  property and  casualty  insurance  underwriting
         operations in 1985,  some of which were then placed into run-off,  with
         the  remainder  sold in 1987.  In  connection  with  those  sales,  A&A
         provided  indemnities  to the  purchasers  for  various  estimated  and
         potential  liabilities,  including  provisions  to cover future  losses
         attributable to insurance pooling arrangements, a stop-loss reinsurance
         agreement,  and actions or omissions by various  underwriting  agencies
         previously  managed  by an A&A  subsidiary.   As of June 30,  2001, the
         liabilities associated with the foregoing

                                       - 10 -

         indemnities and liabilities of insurance underwriting subsidiaries that
         are currently in run-off were  included in  other  liabilities  in  the
         accompanying  condensed consolidated statements of financial  position.
         Such  liabilities  amounted  to  $120   million,   net  of  reinsurance
         recoverables  and  other  assets   of  $161   million,   and  would  be
         substantially  reduced  if  a  February, 2000  ruling from the Court of
         Appeal in England favorable to A&A, in respect of which right to appeal
         has been granted, were upheld in a decision expected in or around 2002.


12.      Contingencies
         -------------

         Aon  and  its  subsidiaries   are  subject  to  numerous  claims,   tax
         assessments and lawsuits that arise in the ordinary course of business.
         The damages  that may be claimed  are  substantial,  including  in many
         instances  claims for punitive or extraordinary  damages.  Accruals for
         these  items have been  provided  to the extent  that losses are deemed
         probable and are estimable.

         In 1998, the Internal Revenue Service (IRS) proposed adjustments to the
         tax of certain Aon  subsidiaries  for the period of 1990 through  1993.
         Most  of  these   adjustments   should  be  resolved   through  factual
         substantiation  of certain  accounting  matters.  However,  the IRS has
         contended  that  retro-rated   extended   warranty   contracts  do  not
         constitute  insurance  for  tax  purposes.  Accordingly,  the  IRS  has
         proposed  a  deferral  of  deductions  for   obligations   under  those
         contracts. The effect of such deferral would be to increase the current
         tax  obligations  of certain  Aon  subsidiaries  by  approximately  $74
         million,  $3 million,  $5 million and $12 million  (plus  interest)  in
         years 1990, 1991, 1992, and  1993, respectively.  Aon believes that the
         IRS's position is without merit and inconsistent with numerous previous
         IRS private letter rulings. Aon has commenced an administrative  appeal
         and intends to contest vigorously such treatment.  Aon believes that if
         the contracts are deemed not to be insurance  for  tax  purposes,  they
         would be recharacterized in such a way that the increased taxes for the
         years in question would be far less than the proposed assessments.

         In the second quarter of 1999,  Allianz Life Insurance Company of North
         America,  Inc.  ("Allianz")  filed an amended  complaint  in  Minnesota
         adding a brokerage  subsidiary of Aon as a defendant in an action which
         Allianz brought against three insurance  carriers reinsured by Allianz.
         These three carriers  provided  certain types of workers'  compensation
         reinsurance to a pool of insurers and to certain  facilities managed by
         Unicover  Managers,  Inc.  ("Unicover"),  a New Jersey  corporation not
         affiliated with Aon.  Allianz alleges that the Aon subsidiary  acted as
         an agent of the three  carriers  when placing  reinsurance  coverage on
         their behalf.  Allianz claims that the  reinsurance it issued should be
         rescinded  or that it  should  be  awarded  damages,  based on  alleged
         fraudulent,  negligent and innocent misrepresentations by the carriers,
         through  their  agents,  including the Aon  subsidiary  defendant.  Aon
         believes that the Aon subsidiary has  meritorious  defenses and the Aon
         subsidiary intends to vigorously defend this claim.

         Except for an action  filed to compel Aon to produce  documents,  which
         has  been  settled,  the  Allianz  lawsuit  is  the  only  lawsuit   or
         arbitration  relating to Unicover  in which any  Aon-related  entity is
         currently a party.

         Certain U.K. subsidiaries of Aon have been required by their regulatory
         body, the Personal  Investment  Authority (PIA), to review advice given
         by those  subsidiaries  to individuals  who bought pension plans during
         the period from April 1988 to June 1994. These reviews have resulted in
         a requirement to pay compensation to clients based on guidelines issued
         by the PIA.  Aon's ultimate exposure  from  the  private  pension  plan
         review, as  presently  calculated,  is  subject

                                       - 11 -



         to a number of variable factors including, among others, general  level
         of  pricing  in  the  equity markets,  the  interest  rate  established
         quarterly for calculating compensation, and the precise scope, duration
         and  methodology of the  review,  including  whether recent  regulatory
         guidance will have to be applied to previously settled claims.

         Although the ultimate  outcome of all matters  referred to above cannot
         be ascertained and liabilities in indeterminate  amounts may be imposed
         on Aon or  its  subsidiaries,  on the  basis  of  present  information,
         amounts already provided, availability of insurance coverages and legal
         advice  received,  it is the opinion of management that the disposition
         or  ultimate  determination  of such  claims  will not have a  material
         adverse effect on the consolidated  financial position of Aon. However,
         it is possible that future  results of operations or cash flows for any
         particular  quarterly or annual period could be materially  affected by
         an unfavorable resolution of these matters.


13.      Acquisitions
         ------------

         In February  2001,  Aon announced that it had entered into a definitive
         agreement  to acquire ASI  Solutions  Incorporated  (ASI),  a worldwide
         provider of human resources  administration and compensation consulting
         services.  The transaction involved an exchange of Aon common stock and
         was completed on May 9, 2001. ASI has been accounted for as a purchase.


         In May  2001,  Aon  announced  that it had  entered  into a  definitive
         agreement to acquire First Extended, Inc., an administrator of extended
         contract   products.   The   transaction   involved   an   exchange  of
         approximately  2 million  shares of  Aon common stock and was completed
         on July 24, 2001.  It will be accounted for as a purchase in accordance
         with  the  new  authoritative  guidance  on  business  combinations and
         goodwill.



14.      Subsequent Event
         ----------------

         In July 2001,  Aon acquired the common stock of two entities controlled
         by Aon's Chairman and Chief  Executive  Officer.  The  acquisition  was
         financed  by  the  issuance of approximately 22 million shares  of  Aon
         common stock and has been accounted for as a purchase. The two acquired
         entities owned,  in the aggregate, approximately 22 million  shares  of
         Aon common stock,  which  will be included in  Treasury Stock, and  had
         additional  net assets totaling  $6 million.  This  transaction did not
         have  a  material  effect on total assets, liabilities or stockholders'
         equity.

                                       - 12 -


                                 AON CORPORATION
                      MANAGEMENT'S DISCUSSION AND ANALYSIS
                OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

                       SECOND QUARTER ENDED JUNE 30, 2001


GENERAL
- -------

Aon has three  operating  segments:  Insurance  Brokerage  and  Other  Services,
Consulting and Insurance  Underwriting.  These segments are based on the type of
client and the services or products delivered.  Aon has a fourth,  non-operating
segment, Corporate and Other.

References  to  organic  revenue  growth  exclude  the  impact of  acquisitions,
dispositions,  transfers,  investment income, foreign exchange and other unusual
items. Within the Insurance Underwriting segment, written premiums are the basis
for the  measurement of organic  growth.  References to income before income tax
are before  minority  interest  related to the  issuance  of 8.205%  mandatorily
redeemable preferred capital securities and the cumulative effect of a change in
accounting principle. For purposes of operating segment discussions, comparisons
against 2000 results exclude special charges.

INFORMATION CONCERNING FORWARD-LOOKING STATEMENTS
- -------------------------------------------------

This quarterly report may contain certain statements relating to future results,
which are  forward-looking  statements  as that term is defined  in the  Private
Securities Litigation Reform Act of 1995. These  forward-looking  statements are
subject to certain risks and  uncertainties  that could cause actual  results to
differ materially from historical results or those  anticipated,  depending on a
variety of factors such as general  economic  conditions in different  countries
around the  world,  fluctuations  in global  equity  and fixed  income  markets,
changes in  commercial  property and casualty  premium  rates,  the  competitive
environment,  the actual cost of resolution of contingent liabilities, the final
form of the business  transformation  plan,  the ultimate cost and timing of the
implementation  thereof,  the actual cost savings and other  benefits  resulting
therefrom,  whether the Company  ultimately  implements the proposed spin-off of
its underwriting operations, and the timing and terms associated therewith.

SPIN-OFF OF UNDERWRITING BUSINESS
- ---------------------------------

As previously  disclosed,  on April 20, 2001, Aon's Board of Directors approved,
in  principle,  a plan to spin-off  its  underwriting  business to Aon's  common
stockholders,  creating two independent, publicly traded companies. The spin-off
would take the form of a tax-free stock  dividend to Aon's common  stockholders.
The transaction is subject to final Board approval, a favorable Internal Revenue
Service ruling, and certain insurance regulatory approvals.


BUSINESS TRANSFORMATION PLAN
- ----------------------------

In November 2000,  Aon's Board of Directors  approved a  comprehensive  business
transformation  plan designed to enhance client service,  significantly  improve
the way Aon  conducts  business  and  improve  profitability  primarily  through
utilization of technology and process redesign.

Implementation of the business  transformation plan began in fourth quarter 2000
and will continue throughout 2001 and into 2002. As originally projected,  total
plan costs, which include transition expenses, are expected to be less than $325
million  on a pretax  basis.  The majority of the plan costs and

                                       - 13 -


savings are related to  the  Insurance  Brokerage  and  Other Services  segment,
principally in the U.S. and the United Kingdom, where most of Aon's offices  and
employees are located. Slightly more than half of the total charges involve cash
outlays for severance payments related to job eliminations.   The net reductions
of approximately  3,000  positions are in line with our  previous  announcements
after  considering  new   hires  resulting  from   Aon's  evaluation   of   work
processes, changing job functions and service center locations.

In connection with the plan, Aon recorded pretax special charges of $146 million
($89 million after tax or $0.33 per share) during second  quarter 2001.  For six
months,  pretax  special  charges were $218 million  ($133  million after tax or
$0.49 per share). For the quarter,  special charges of $85 million were incurred
which related to termination benefits and involved notification to approximately
2,000  employees.  Charges of $61 million were  incurred  for asset  impairment,
primarily  relating  to the  abandonment  of systems  and  equipment,  and other
charges.  Year-to-date,  charges of $108  million  were taken  which  related to
termination benefits and involved about 3,200 employees. As part of the business
transformation, Aon examined its marginal return non-core business alliances and
took a pretax charge of $50 million, of which $38 million was taken in the first
quarter,  to end Aon's involvement in certain joint ventures and service partner
relationships  that did not meet profitability  hurdles.  It also allowed Aon to
further  reduce  headcounts.  Charges of $60  million  were  incurred  for asset
impairments, primarily relating to the abandonment of systems and equipment, and
other  charges.  Transition  costs,  primarily  related  to our  core  operating
businesses,  were  approximately $2 million in the second quarter and $5 million
for the first six months 2001 and  consisted  of  consulting  fees and  employee
benefits.  Future  transition costs, that are not expected to exceed $25 million
in total, are related to the transition phase from previous  operating models to
reconfigured operating platforms and will impact future periods.

Annualized  pretax savings from the plan are estimated to be approximately  $150
million to $200  million.  The  annualized  savings are expected to begin at the
lower end of the range in fourth quarter 2001, and increase  within the range in
2002 as  transition  costs  related  to the  business  transformation  plan  are
eliminated.  Savings  generated  to  date in  2001  were  offset,  in  part,  by
transition  costs.  As Aon progresses  through the next several  quarters,  more
business  process change and additional  position  eliminations  will drive cost
savings. As expected, temporary revenue growth rate declines occurred related to
the  transformation  and may continue to occur during the  implementation of the
plan.

CONSOLIDATED RESULTS
- --------------------

Total revenue  increased $98 million or 5% when compared to second quarter 2000.
Excluding  the effect of foreign  exchange  rates,  revenues rose 8% over second
quarter 2000,  attributable to growth in brokerage  commissions and fees,  which
more than offset a decline in investment  income.  Consolidated  revenue for the
operating segments grew approximately 8% on an organic basis over last year. For
the first six months,  revenue rose $99 million or 3% over last year.  Excluding
the effects of foreign exchange rates,  revenues  increased 6%.  Improvements in
brokerage  commissions and fees as well as premiums earned were somewhat negated
by a decline in investment income.

Brokerage  commissions  and fees increased $144 million or 12% in second quarter
2001 and $220  million  or 9% on a  year-to-date  basis.  This  improvement  was
primarily  from  organic  growth,  business  combination  activity,   especially
Actuarial  Sciences  Associates,  Inc.  (ASA)  which was  acquired in the fourth
quarter 2000,  increased  new business and the impact of increased  property and
casualty premium rates.

Premiums and other is primarily  related to insurance  underwriting  operations.
Premiums and other  improved $1 million over second  quarter 2000, and increased
$41 million or 4% in the first six months of 2001, compared with the same period
last year.  In the second  quarter,  growth in the accident and health lines was
offset by loss of some accounts in the warranty business,  a general slowdown of
the market and  unfavorable

                                       - 14 -


foreign exchange rates. The increase in premiums earned for the first six months
primarily  reflects new  business  initiatives, continued organic growth and the
impact of acquisitions.

Investment  income,  which  includes  related  expenses  and  income  or loss on
disposals and  impairments,  decreased  significantly in both the second quarter
and six months 2001 when compared to prior year,  primarily  reflecting  reduced
valuations of equity  investments in limited  partnerships  for both the quarter
and year-to-date.  The six-month  comparison is also negatively  impacted by the
impairment  recorded for certain directly owned equity  investments in the first
quarter 2001.  Revenues  from private  equity  investments  fluctuate due to the
inherent  volatility of equity  investments.  Investment  income from  insurance
brokerage and other services, and consulting  operations,  primarily relating to
fiduciary  funds,  decreased $7 million and $3 million in second quarter and six
months 2001,  respectively,  compared to similar periods in 2000, primarily as a
result of declines in interest rates.

Total  expenses  increased  $262  million or 16% over  second  quarter  2000 due
partially to the inclusion of special charges in 2001. Total expenses, excluding
the special charges,  rose 7%. General expenses increased $261 million or 21% in
the quarter primarily  reflecting special charges of $146 million related to the
business transformation plan, along with investments in new business initiatives
and  technology.  Interest  expense  declined $2 million or 6%,  driven by lower
average debt levels and lower short-term interest rates.

For six months,  total expenses  increased $433 million or 14% over 2000, driven
by the inclusion of special charges this year.  Excluding  these charges,  total
expenses  rose $215 million or 7%.  General  expenses  grew $386 million or 15%,
reflecting  special  charges of $218 million,  along with  expenditures  for new
business initiatives and technology.  Benefits to policyholders rose $43 million
or 8% as a result of new underwriting initiatives along with an unusual increase
in warranty claims during the first quarter 2001 related to an isolated  program
that will not affect future quarters.  Interest expense  increased $3 million or
5% compared to prior year attributed to the substitution of short-term debt with
long-term debt in second quarter 2000.

For the  quarter,  income  before  income tax declined  significantly  from $228
million in 2000 to $64 million in 2001, due principally to the inclusion of 2001
special charges ($146 million) with no comparable  amount in second quarter 2000
as well as  non-cash  investment  results (a negative  $36  million  change on a
period-to-period  comparison).  Similarly,  six month 2001 results declined from
2000 by 75% to $112 million  from $446  million due to 2001  special  charges of
$218 million and a decline in consolidated investment income of $162 million.

As a result of these  factors,  second  quarter 2001 net income  declined to $29
million ($0.11 per dilutive  share) compared to $129 million ($0.49 per dilutive
share) in 2000. Basic net income per share was $0.11 and $0.50 in second quarter
2001 and 2000,  respectively.  For the first six months 2001 net income declined
to $48 million  ($0.17 per dilutive  share)  compared to $245 million ($0.93 per
dilutive  share) in 2000.  In 2000,  the  company  adopted  the  Securities  and
Exchange  Commission's  Staff  Accounting  Bulletin  101,  which  resulted  in a
one-time  cumulative  non-cash charge of $7 million after-tax ($0.03 per share).
Basic net income per  share,  was $0.18 and $0.94 for the first six months  2001
and 2000,  respectively.  Dividends on the redeemable  preferred stock have been
deducted from net income to compute income per share. The effective tax rate was
39% for both second quarter and six months 2001 and 2000, respectively.

                                       - 15 -


OPERATING SEGMENTS
- ------------------

INSURANCE BROKERAGE AND OTHER SERVICES
- --------------------------------------

The Insurance Brokerage and Other Services segment consists principally of Aon's
retail,  reinsurance  and  wholesale  brokerage  operations  as well as managing
underwriting,  actuarial,  loss control,  claims,  alternative risk transfer and
premium financing services.  This segment represented 60% and 61% of Aon's total
revenues for the second quarter and first six months of 2001, respectively.

Second  quarter 2001  Insurance  Brokerage and Other  Services  revenue was $1.2
billion,  up 8% over last year.  Excluding foreign exchange,  revenues rose 11%.
Year-to-date,  revenues of $2.3 billion  improved 6% over the previous year. The
increase in both periods reflects strong organic growth, especially in the claim
services,  international,  wholesale and reinsurance  brokerage  sectors.  Lower
investment  income,  driven by lower  interest  rates,  negatively  impacted the
quarter and year-to-date comparisons by $7 million and $4 million, respectively.

U.S. revenue of $602 million for the quarter was up 10% from 2000. For the first
six months,  revenues climbed 7% to $1.1 billion. For both periods, the increase
reflects increased new business,  growth in U.S. specialty operations,  improved
pricing and acquisitions,  which more than offset the direct and indirect impact
of the business  transformation  plan. As  anticipated,  new account  generation
during  2001  grew at a  slower  rate  in  certain  retail  brokerage  units  as
operational  changes were implemented to achieve long-term benefits of the plan.
Commercial  property and casualty  premium rate  increases were evident for most
lines of coverage and client demand for risk retention programs and services has
risen  along with the upward  trend in premium  rates.  U. K. and  Continent  of
Europe  revenues of $399 million for the second quarter and $844 million for the
first six months 2001 increased 5% and 4%,  respectively,  from 2000,  primarily
due to organic  growth and  acquisitions.  The impact of foreign  exchange rates
partially  offset this  revenue  growth.  Rest of world  revenue  increased  $14
million or 10% over  second  quarter  2000 and $25 million or 10% over the first
six months 2000 reflecting strong organic growth, new business,  and to a lesser
extent,  the  impact of  acquisitions.  In the  international  retail  brokerage
operations, premium rate comparisons have improved slightly over last quarter.

Pretax income was $78 million for the second quarter 2001. Excluding this year's
special  charges,  pretax  income  of $195  million  rose 7% over  2000.  Pretax
margins,  excluding the charges,  were 16.9% in the quarter compared to 17.1% in
2000.  The margin  decline  was  driven by lower  interest  rates on  investment
income, along with significant growth in our claims service business,  which has
lower margins.  These items more than offset  business  transformation  savings,
which includes a pension curtailment  pretax gain of $8 million.   Year-to-date,
pretax income was $204 million. Excluding special charges, pretax income rose 8%
to $391 million.  Pretax  margins  excluding  the  charges were 17.2% for  2001,
versus 16.9% last year. The margin improvement was driven in part from  business
transformation  savings, but was negatively impacted by an increasing percentage
of lower margin claims service business and somewhat lower investment income.

CONSULTING
- ----------

The  consulting  segment  provides  a full  range  of  services  related  to the
management of human capital, benefits and business processes. These services are
delivered to a predominately corporate clientele utilizing four practice groups:
employee benefits, compensation,  management consulting and employment practices
outsourcing.  The  acquisition  of  ASI  Solutions  Incorporated  (ASI)  further
strengthened Aon's employment practices outsourcing and compensation  consulting
services.  This segment  accounted for 12% of Aon's total  revenues for both the
quarter and first six months of 2001.

                                       - 16 -


Second quarter 2001 revenue increased 27% to $229 million.  Excluding the impact
of a strong U.S. dollar,  revenues grew 30%. For the first six months,  revenues
of $441 million  represent a 24%  increase  over 2001.  Excluding  the impact of
foreign  exchange  rates,  the growth rate was 27%. For the second quarter 2001,
revenue grew 9% on an organic  basis.  On a global  basis,  the  improvement  in
revenue for both periods was influenced by acquisition activity,  especially the
inclusion of ASA acquired in fourth quarter 2000,  and to a lesser extent,  ASI,
acquired  in the second quarter 2001,  as well as organic growth.  Client demand
for solutions that enhance  workforce productivity continued.

For the  quarter,  U.S.  revenue of $157  million  was up 44% from  2000,  while
year-to-date  revenue of $292  represents a 40% increase.  In both periods,  the
improvement  reflects the  acquisition of ASA and strong  fundamental  operating
performance,  particularly in the employee  benefits area. U.K. revenue declined
from 2000 by 7% and 8% for the  second  quarter  and six  months,  respectively,
reflecting  the sale of the financial  planning  consulting  business last year,
along with unfavorable foreign exchange rates.  Continent of Europe revenue rose
$2 million for the quarter and $2 million for six months compared to 2000.

Pretax  income was $24 million for the quarter.  Excluding  this year's  special
charges, pretax income improved 30% to $30 million. Year-to-date,  pretax income
was $48 million. Excluding special charges, pretax income of $55 million was 31%
better  than 2000.  Pretax  margins in this  segment  were 13.1% in the  quarter
before special charges compared to 12.8% in 2000. For six months, pretax margins
before special charges rose from 11.8% in 2000 to 12.5% in 2001.  Revenue growth
outpaced  higher  staffing  costs,  driven by the  inclusion  of the ASA and ASI
acquisitions,  as well as expenses  due to the growth of the business and higher
technology costs.

INSURANCE UNDERWRITING
- ----------------------

The  Insurance  Underwriting  segment  provides  accident  and  health  and life
insurance  coverage through  distribution  networks,  most of which are directly
owned by Aon's  subsidiaries,  and  extended  warranty and property and casualty
insurance products. This segment represented 29% and 30% of Aon's total revenues
for the second quarter and first six months of 2001, respectively.

Revenue was $548 million in second  quarter 2001,  down 1% from 2000.  Excluding
the impact of foreign exchange, revenue growth was 2%. Year-to-date, revenues of
$1.1  billion  in 2001 were a 3%  increase  over 2000.  Excluding  the impact of
exchange rates,  revenues rose 6%. For both periods,  improvement over last year
was driven by the  development of new product  initiatives  and higher volume of
business in accident and health products, which continued to expand distribution
through worksite  marketing  programs.  This growth more than offset the loss of
certain accounts in the electronics and special warranty businesses, declines in
other policyholder liabilities and the slowing general economy.

U.S.  revenue  declined $1 million in the second quarter 2001 to $393 million as
growth in revenues  for accident  and health  products,  due in part to acquired
business,  as well as new  product  initiatives,  were offset by declines in the
mechanical  and  electronic  warranty  products  along  with  declines  in other
policyholder  liabilities.  For six months 2001,  revenues  rose 4% from 2000 to
$799 million,  reflecting higher revenues for accident and health products,  due
in part to acquired  business,  as well as new product  initiatives,  which more
than  offset a decline in  mechanical  warranty  products.  United  Kingdom  and
Continent of Europe  revenue of $103  million fell 6% during the quarter,  while
year-to-date,  revenues fell 1% to $211 million.  Unfavorable  foreign  exchange
rates and the slowdown of business in the warranty area offset organic growth in
the accident and health  sector.  Rest of world revenue was $52 million and $105
million for the second  quarter  and first six months 2001,  up 6% over both the
second quarter and year-to-date periods in 2000, driven principally by growth in
Latin America.

                                       - 17 -


Pretax  income was $56 million for the quarter.  Excluding  this year's  special
charges,  pretax  income  was flat to last  year at $79  million.  Year-to-date,
pretax income was $123 million. Excluding special charges, pretax income of $147
million was 1% better than 2000.  Pretax  margins in this  segment were 14.4% in
the quarter  before special  charges  compared to 14.3% in 2000. For six months,
pretax margins before special  charges fell from 13.5% in 2000 to 13.2% in 2001.
For both periods in 2001, new underwriting  initiatives drove premium growth but
also  resulted in  increased  benefits to  policyholders.  For the  year-to-date
comparison,  an unusual  increase in warranty  claims  occurred during the first
quarter  2001  related  to an  isolated  program  that  will not  affect  future
quarters.


NON-OPERATING SEGMENT
- ---------------------

CORPORATE AND OTHER
- -------------------

Revenue in this  category  consists  primarily of investment  income  (including
income  or loss  on  disposals,  along  with  impairment  losses)  which  is not
otherwise  reflected in the results of the operating  segments.  Invested assets
and related  investment  income not directly  required to support the  insurance
brokerage and consulting  businesses,  together with the assets in excess of net
policyholder  liabilities of the underwriting businesses and related income, are
allocated to the  Corporate  and Other  segment.  Corporate  and Other  expenses
include general  expenses,  administrative  and certain  information  technology
costs, interest expense and goodwill amortization.

Corporate  and Other  revenue  for the second  quarter  2001 was a negative  $14
million,  versus positive revenue of $22 million in the second quarter 2000. For
six months 2001, revenue was a negative $99 million,  versus positive revenue of
$52 million last year. The falloff in revenue in both periods primarily reflects
reduced  valuations  for  equity  investments  in  limited   partnerships.   The
year-to-date  comparison is also affected by the write-down of certain  directly
owned equity investments in the first quarter 2001. Revenues from private equity
investments  fluctuate  due to the inherent  volatility  of equity  investments.
Limited partnership investments require longer time horizons to generate income.

Corporate  and Other  expenses for the quarter  were $80 million,  up $2 million
from the same  period  last year.  Expenses  in this  segment  are  composed  of
goodwill amortization,  interest expense and general expenses.  Interest expense
fell $2 million or 6% compared to prior year, reflecting lower interest rates as
well as lower debt levels. General expenses rose $4 million or 25% due to higher
occupancy costs, professional fees and human resource initiatives. For the first
six months of 2001,  expenses were $164 million,  an increase of $8 million from
the comparable period in 2000. Goodwill amortization rose $2 million as a result
of new  acquisitions.  Interest  expense  increased $3 million compared to prior
year,  reflecting  an extension of debt duration in second  quarter 2000,  while
general  expenses  rose $3  million,  resulting  from  higher  occupancy  costs,
professional fees and human resource initiatives.

The revenue and expense  comparisons  discussed above contributed to the overall
Corporate  and Other pretax loss of $94 million in the quarter  versus a loss of
$56 million last year.  The  year-to-date  loss of $263 million was $159 million
worse than 2000.

                                       - 18 -

                        CASH FLOW AND FINANCIAL POSITION
                          AT THE END OF FIRST HALF 2001

Cash flows from operating  activities  represent the net income earned by Aon in
the reported  periods adjusted for non-cash charges as well as changes in assets
and liabilities.  Cash flows provided by operating  activities for the first six
months 2001 were $296  million,  a $34 million  increase over the same period in
2000.  The increase  represents,  in part, the net cash flow  impact of  special
charges and purchase accounting liabilities which was less than last year. First
half 2001 reflects  after-tax  special  charges of  $133  million,  adjusted for
actual cash expended.  First half 2000 reflects only actual  payments on special
charge  and  purchase  accounting  liabilities  previously  established.   Other
receivables and liabilities  improved  due  to the timing of sold receivables at
our premium financing group.  This was  partially offset by the timing of income
tax payments  and  refunds.  The  non-cash effect of  lower  valuations  on  the
company's limited partnership portfolio, coupled with impairments on investments
and loss on disposals, was offset partially by lower net income.

Investing  activities  used  cash of  $278  million.  Cash  of $66  million  was
provided  during  first  half  2001 from the net sale of  investments.  This was
offset by the net purchase of short-term  investments of $162 million. Cash used
for  acquisition  activity  during  the first six months  2001 was $70  million,
reflecting both brokerage and consulting acquisitions.

Cash of $366  million was used  during the first six months  2001 for  financing
activities,  which was $308 million  more than was utilized in 2000.  The higher
usage  of cash  from  last  year is  primarily  due a  reduction  of  short-term
borrowings in 2001 versus  increasing  short-term  debt during last year's first
half.  In  addition,  $250  million of  long-term  debt was issued in the second
quarter 2000. Cash was used to pay dividends of $117 million on common stock and
$1 million on redeemable preferred stock during first half 2001.

Aon's operating subsidiaries anticipate that there will be adequate liquidity to
meet their needs in the foreseeable future.  Aon's liquidity needs are primarily
for  servicing  its debt and for the payment of  dividends  on stock  issues and
capital securities.  The businesses of Aon's operating  subsidiaries continue to
provide  substantial  positive  cash  flow.  Brokerage  cash  flow has been used
primarily  for  business  reinvestment,  acquisition  financing  and payments of
special charge and purchase accounting liabilities. Aon anticipates continuation
of the company's positive cash flow, the ability of the parent company to access
adequate short-term lines of credit, and sufficient cash flow.

Due to the contractual nature of its insurance policyholder  liabilities,  which
are primarily intermediate to long-term in nature, Aon has invested primarily in
fixed  maturities.  With a carrying  value of $2.2  billion,  Aon's  total fixed
maturity  portfolio is invested primarily in investment grade holdings (95%) and
has a fair value, which is 98.2% of amortized cost at June 30, 2001.

Total  assets  increased  $215 million to $22.5  billion  since  year-end  2000.
Invested  assets at June 30, 2001 decreased $55 million from year-end  levels as
higher levels of short-term  investments  and equity  securities  were offset by
lower fixed  maturity  investments  as well as lower  valuations  and impairment
charges in other  investments.  The  amortized  cost and fair value of less than
investment  grade fixed maturity  investments at June 30, 2001 were $129 million
and $116  million,  respectively.  The carrying  value of  non-income  producing
investments  in Aon's  portfolio  at June 30, 2001 was $63  million,  or 1.1% of
total invested assets.

                                       - 19 -


Short-term  borrowings  decreased  at the  end of  second  quarter  2001 by $105
million when compared to year-end  2000.  Notes payable  decreased at the end of
second  quarter 2001 by $52 million when  compared to year-end 2000 , reflecting
repayment of foreign debt.

Stockholders'  equity  increased  $82 million in first half 2001,  reflecting an
increase in paid-in  additional  capital of $93  million,  as a result of shares
issued  for the ASI  acquisition.  In  addition,  equity  rose  because of a net
decrease  in  treasury  stock of $76  million, reflecting shares issued, and net
income  of $48  million. Partially  offsetting  this  increase  were net foreign
exchange  losses  of  $46  million  and  dividends paid to stockholders of  $118
million.   Unrealized investment gains and losses and foreign exchange gains and
losses   fluctuations  from  period  to  period  are  largely  based  on  market
conditions.

Stockholders'  equity per share of $13.02 was unchanged  from December 31, 2000.
The higher  equity  balance  was offset by the  increase in the number of shares
outstanding.


REVIEW BY INDEPENDENT AUDITORS
- ------------------------------

The condensed  consolidated  financial  statements at June 30, 2001, and for the
six months then ended have been reviewed, prior to filing, by Ernst & Young LLP,
Aon's independent auditors, and their report is included herein.

                                       - 20 -


INDEPENDENT ACCOUNTANTS' REVIEW REPORT



Board of Directors and Stockholders
Aon Corporation

We have reviewed the accompanying  condensed consolidated statement of financial
position of Aon  Corporation  as of June 30,  2001,  and the  related  condensed
consolidated  statements  of  income for the  three-month and six-month  periods
ended June 30, 2001 and 2000, and the condensed consolidated  statements of cash
flows for the six-month periods ended  June 30, 2001 and 2000.  These  financial
statements are the responsibility of the Company's management.

We  conducted  our  reviews in  accordance  with  standards  established  by the
American  Institute  of  Certified  Public  Accountants.  A  review  of  interim
financial  information consists principally of applying analytical procedures to
financial  data, and making  inquiries of persons  responsible for financial and
accounting matters. It is substantially less in scope than an audit conducted in
accordance  with auditing  standards  generally  accepted in the United  States,
which will be performed  for the full year with the  objective of  expressing an
opinion regarding the financial statements taken as a whole. Accordingly,  we do
not express such an opinion.

Based on our reviews, we are not aware of any material modifications that should
be made to the accompanying condensed consolidated financial statements referred
to above  for them to be in  conformity  with  accounting  principles  generally
accepted in the United States.

We have  previously  audited,  in accordance with auditing  standards  generally
accepted in the United States, the consolidated  statement of financial position
of Aon  Corporation  as of  December  31,  2000,  and the  related  consolidated
statements  of income,  stockholders'  equity,  and cash flows for the year then
ended,  not  presented  herein,  and in our report  dated  February 8, 2001,  we
expressed an unqualified opinion on those consolidated financial statements.  In
our  opinion,   the  information  set  forth  in  the   accompanying   condensed
consolidated  statement of financial position as of December 31, 2000, is fairly
stated, in all material respects,  in relation to the consolidated  statement of
financial position from which it has been derived.




                                                 ERNST & YOUNG LLP

Chicago, Illinois
August 9, 2001

                                       - 21 -


                                     PART II
                                     -------

                                OTHER INFORMATION
                                -----------------


ITEM 2. CHANGES IN SECURITIES AND USE OF PROCEEDS

Pursuant to an  Agreement  and Plan of Merger  dated July 16, 2001 (the  "Merger
Agreement") among Aon, Holdco #1, Inc., a Delaware  corporation and wholly owned
subsidiary of Aon ("Holdco  #1"),  Holdco #2, Inc., a Delaware  corporation  and
wholly owned  subsidiary  of Aon ("Holdco  #2"),  Ryan  Holding  Corporation  of
Illinois,  a Delaware  corporation  ("RHC"),  Ryan  Enterprises  Corporation  of
Illinois, a Delaware  corporation ("REC"),  Patrick G. Ryan, Shirley W. Ryan and
the  stockholders  of RHC and REC, who  consisted  solely of members of the Ryan
family or trusts controlled by members of the Ryan family,  (1) Holdco #1 merged
with and into  RHC  (the  "RHC  Merger")  with  the  result  that the  surviving
corporation  became  a  wholly  owned  subsidiary  of Aon and the  stock  of RHC
outstanding  immediately prior to the RHC Merger was converted into an aggregate
13,992,089  shares of Aon Common  Stock,  and (2) Holdco #2 merged with and into
REC (the "REC Merger" and together with the RHC Merger,  the "Mergers") with the
result that the surviving  corporation  became a wholly owned  subsidiary of Aon
and the outstanding stock of REC outstanding immediately prior to the REC Merger
was converted  into an aggregate  8,372,348  shares of Aon Common Stock.  At the
time of the RHC  Merger  and the REC  Merger,  the  sole  assets  of RHC and REC
consisted  of an  aggregate  of  22,364,437  shares of Aon Common Stock and cash
aggregating  $6 million more than the balance sheet  liabilities of RHC and REC,
which consisted solely of bank indebtedness.  The number of shares  beneficially
owned  by the  Ryan  family  after  the  Mergers  is  the  same  as  the  number
beneficially owned by them prior to such Mergers.

The  Mergers  did  not  involve  any  underwriters,  underwriting  discounts  or
commissions,  or any public offering, and Aon believes that each transaction was
exempt  from the  registration  requirements  of the  Securities  Act of 1933 by
virtue of Section 4(2) thereof  regarding  transactions  not  involving a public
offering and Rule 506 of Regulation D promulgated thereunder.  The recipients of
securities in the Mergers  represented their intention to acquire the securities
for  investment  only and not with a view to or for sale in connection  with any
distribution  therefor,  such  securities  were  restricted  as to transfers and
appropriate  legends  were affixed to the  share  certificates  issued  for  the
Mergers.



ITEM 6.           EXHIBITS AND REPORTS ON FORM 8-K

         (a)      Exhibits - The  exhibits  filed with this report are listed on
                  --------
                  the attached Exhibit Index.

         (b)      Reports on Form 8-K - The Registrant  filed one current report
                  -------------------
                  on Form 8-K dated April 20,  2001 for the  quarter  ended June
                  30, 2001, announcing that the company's Board of Directors had
                  approved,  in principle,  a plan to spin off its  underwriting
                  business to its common shareholders. The following exhibit was
                  included in the report: Exhibit 99 - Press Release.

                                       - 22 -


SIGNATURE

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.


                                 Aon Corporation
                                 (Registrant)

August 14, 2001                  /s/ Harvey N. Medvin
                                 --------------------
                                 HARVEY N. MEDVIN
                                 EXECUTIVE VICE PRESIDENT AND
                                 CHIEF FINANCIAL OFFICER
                                 (Principal Financial and Accounting Officer and
                                  authorized signatory on behalf of Registrant)

                                       - 23 -



AON CORPORATION
- ---------------

Exhibit Number
In Regulation S-K


Item 601 Exhibit Table
- ----------------------

(10.1)   Agreement   and  Plan  of  Merger,   dated  July  16,  2001  among  Aon
         Corporation,  Ryan Holding  Corporation of Illinois,  Ryan  Enterprises
         Corporation of Illinois,  Holdco #1, Inc., Holdco #2, Inc.,  Patrick G.
         Ryan, Shirley W. Ryan and the stockholders of Ryan Holding  Corporation
         of Illinois and of Ryan  Enterprises  Corporation of Illinois set forth
         on the signature pages thereto.

(10.2)   Stock Restriction  Agreement dated July 16, 2001 among Aon Corporation,
         Patrick G. Ryan,  Shirley W. Ryan,  Patrick G. Ryan,  Jr.,  Robert J.W.
         Ryan,  the Corbett  M.W.  Ryan Living  Trust dated July 13,  2001,  the
         Patrick G. Ryan Living Trust dated July 10,  2001,  the Shirley W. Ryan
         Living  Trust dated July 10, 2001,  the 2001 Ryan  Annuity  Trust dated
         April 20,  2001 and the Family GST Trust under the PGR 2000 Trust dated
         November 22, 2000.

(10.3)   Escrow Agreement dated July 16, 2001 among Aon Corporation,  Patrick G.
         Ryan,  Shirley W. Ryan,  Patrick G. Ryan,  Jr.,  Robert J.W.  Ryan, the
         Corbett M.W. Ryan Living Trust dated July 13, 2001, the Patrick G. Ryan
         Living  Trust dated July 10,  2001,  the  Shirley W. Ryan Living  Trust
         dated July 10, 2001,  the 2001 Ryan Annuity  Trust dated April 20, 2001
         and the Family GST Trust  under the PGR 2000 Trust dated  November  22,
         2000 and American National Bank and Trust Company of Chicago, as escrow
         agent.


(12) Statements regarding Computation of Ratios.

         (a)      Statement regarding  Computation of Ratio of Earnings to Fixed
                  Charges.

         (b)      Statement regarding  Computation   of  Ratio  of  Earnings  to
                  Combined Fixed Charges and Preferred Stock Dividends.


(15) Letter re: Unaudited Interim Financial Information

                                       - 24 -



                                                                                                                   EXHIBIT 12(a)

                                            AON CORPORATION AND CONSOLIDATED SUBSIDIARIES
                                              COMBINED WITH UNCONSOLIDATED SUBSIDIARIES
                                          COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES


                                                  SIX MONTHS ENDED
                                                     JUNE 30,                      YEARS ENDED DECEMBER 31,
                                               --------------------- --------------------------------------------------------
 (millions except ratios)                        2001        2000       2000       1999        1998       1997        1996
                                               ---------  ---------- ----------  ---------  ----------  ---------  ----------

                                                                                                  
 Income from continuing operations
    before provision for income taxes
    and minority interest (1)                     $ 112       $ 446    $   854      $ 635     $   931      $ 542       $ 446

 ADD BACK FIXED CHARGES:

    Interest on indebtedness                         67          64        140        105          87         70          45

    Interest on ESOP                                  -           -          -          1           2          3           4

    Portion of rents representative of
      interest factor                                27          25         54         49          51         44          29

                                               ---------  ---------- ----------  ---------  ----------  ---------  ----------
         INCOME AS ADJUSTED                       $ 206       $ 535    $ 1,048      $ 790     $ 1,071      $ 659       $ 524
                                               =========  ========== ==========  =========  ==========  =========  ==========


 FIXED CHARGES:

    Interest on indebtedness                      $  67       $  64    $   140      $ 105     $    87      $  70       $  45

    Interest on ESOP                                  -           -          -          1           2          3           4

    Portion of rents representative of
       interest factor                               27          25         54         49          51         44          29

                                               ---------  ---------- ----------  ---------  ----------  ---------  ----------
         TOTAL FIXED CHARGES                      $  94       $  89    $   194      $ 155     $   140      $ 117       $  78
                                               =========  ========== ==========  =========  ==========  =========  ==========

 RATIO OF EARNINGS TO FIXED CHARGES                 2.2         6.0        5.4        5.1         7.6        5.6         6.7
                                               =========  ========== ==========  =========  ==========  =========  ==========

<FN>

(1)   Income from continuing  operations  before  provision for income taxes and
      minority  interest  includes  special  charges of $218 million for the six
      months ended June 30, 2001 and $82 million, $313 million, $172 million and
      $90 million for the years ended  December 31, 2000,  1999,  1997 and 1996,
      respectively.
</FN>







                                                                                                                   EXHIBIT 12(b)

                                         AON CORPORATION AND CONSOLIDATED SUBSIDIARIES
                                           COMBINED WITH UNCONSOLIDATED SUBSIDIARIES
                                  COMPUTATION OF RATIO OF EARNINGS TO COMBINED FIXED CHARGES
                                                 AND PREFERRED STOCK DIVIDENDS


                                                   SIX MONTHS ENDED
                                                       JUNE 30,                       YEARS ENDED DECEMBER 31,
                                                ---------------------- ----------------------------------------------------------
 (millions except ratios)                          2001        2000       2000        1999        1998        1997       1996
                                                ----------  ---------- ----------- ----------  ----------  ---------- -----------

                                                                                                      
 Income from continuing operations
    before provision for income taxes
    and minority interest (1)                       $ 112       $ 446     $   854      $ 635     $   931       $ 542       $ 446

 ADD BACK FIXED CHARGES:

    Interest on indebtedness                           67          64         140        105          87          70          45

    Interest on ESOP                                    -           -           -          1           2           3           4

    Portion of rents representative of
      interest factor                                  27          25          54         49          51          44          29

                                                ----------  ---------- ----------- ----------  ----------  ---------- -----------
         INCOME AS ADJUSTED                         $ 206       $ 535     $ 1,048      $ 790     $ 1,071       $ 659       $ 524
                                                ==========  ========== =========== ==========  ==========  ========== ===========


 FIXED CHARGES AND PREFERRED STOCK DIVIDENDS:

    Interest on indebtedness                        $  67       $  64     $   140      $ 105     $    87       $  70       $  45

    Preferred stock dividends                          35          35          70         70          70          82          29

                                                ----------  ---------- ----------- ----------  ----------  ---------- -----------
         INTEREST AND DIVIDENDS                       102          99         210        175         157         152          74

    Interest on ESOP                                    -           -           -          1           2           3           4

    Portion of rents representative of
       interest factor                                 27          25          54         49          51          44          29

                                                ----------  ---------- ----------- ----------  ----------  ---------- -----------
         TOTAL FIXED CHARGES AND PREFERRED
             STOCK DIVIDENDS                        $ 129       $ 124     $   264      $ 225     $   210       $ 199       $ 107
                                                ==========  ========== =========== ==========  ==========  ========== ===========

 RATIO OF EARNINGS TO COMBINED FIXED
   CHARGES AND PREFERRED STOCK DIVIDENDS (2)          1.6         4.3         4.0        3.5         5.1         3.3         4.9
                                                ==========  ========== =========== ==========  ==========  ========== ===========

<FN>
(1)   Income from continuing  operations  before  provision for income taxes and
      minority  interest  includes  special  charges of $218 million for the six
      months ended June 30, 2001 and $82 million, $313 million, $172 million and
      $90 million for the years ended  December 31, 2000,  1999,  1997 and 1996,
      respectively.

(2)   Included in total fixed  charges and  preferred  stock  dividends  are $33
      million for the six months  ended June 30, 2001 and 2000,  $66 million for
      the years ended December 31, 2000,  1999 and 1998, and $64 million for the
      year  ended  December  31,  1997,  of pretax  distributions  on the 8.205%
      mandatorily  redeemable  preferred capital securities which are classified
      as "minority interest" on the condensed consolidated statements of income.
</FN>




                                                                      Exhibit 15


Board of Directors and Stockholders
Aon Corporation


We are aware of the incorporation by reference in the Registration Statements of
Aon  Corporation  ("Aon")  described in the following  table of our report dated
August  9,  2001  relating  to  the  unaudited  condensed  consolidated  interim
financial  statements of Aon Corporation  that are included in its Form 10-Q for
the quarter ended June 30, 2001:

         Registration Statement
         ----------------------
         Form            Number               Purpose
         ----            ------               -------

         S-8          33-27984          Pertaining to Aon's savings plan
         S-8          33-42575          Pertaining to Aon's stock award plan and
                                          stock option plan
         S-8          33-59037          Pertaining to Aon's stock award plan and
                                          stock option plan
         S-4          333-21237         Offer to exchange  Capital Securities of
                                          Aon Capital A
         S-3          333-50607         Pertaining  to   the   registration   of
                                          369,000 shares of common stock
         S-8          333-55773         Pertaining  to Aon's  stock  award plan,
                                          stock  option  plan and  employee
                                          stock purchase plan
         S-3          333-78723         Pertaining to the  registration  of debt
                                           securities,   preferred   stock   and
                                           common stock
         S-3          333-49300         Pertaining   to   the   registration  of
                                           3,864,824 shares of common stock
         S-4          333-57706         Pertaining to the  registration of up to
                                           3,852,184 shares of common stock
         S-3          333-65624         Pertaining  to   the   registration   of
                                           2,000,000 shares of common stock

Pursuant to Rule 436(c) of the  Securities Act of 1933, our report is not a part
of the registration  statements  prepared or certified by accountants within the
meaning of Section 7 or 11 of the Securities Act of 1933.


                                                 ERNST & YOUNG LLP



Chicago, Illinois
August 9, 2001