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 MARCH 31, 1998

                                       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.)



123 N. WACKER DR, CHICAGO, ILLINOIS              60606
- - - - - - - - - - - - - - - - - -----------------------------------              -----
(Address of Principal Executive Offices)        (Zip Code)


             (312) 701-3000
             --------------
     (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  12 months (or for such  shorter  period that the
Registrant was required to file such reports),  and (2) has been subject to such
filing requirements for the past 90 days. YES  X  NO
                                              ---    ---    

Number of shares of common stock outstanding:

                                                      No. Outstanding
           Class                                       as of 3-31-98
           -----                                       -------------
   $1.00 par value Common                               168,651,179


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


(millions)                                              As of       As of
                                                      March 31,   March 31,
                                                         1998        1997
                                                     ----------  ----------
ASSESTS                                             (Unaudited)

Investments
  Fixed maturities at fair value                     $  3,044.5  $  3,143.6
  Equity securities at fair value                         714.8       806.3
  Short-term investments                                2,075.0     1,697.7
  Other investments                                       282.8       274.5
                                                     ----------  ----------
      Total investments                                 6,117.1     5,922.1


Cash                                                    1,010.0     1,084.7

Receivables
  Insurance brokerage and consulting
   services                                             5,292.0     5,320.5
  Premiums and other                                      993.5       862.6
  Accrued investment income                                68.8        66.8
                                                     ----------  ----------
      Total receivables                                 6,354.3     6,249.9



Intangible assets                                       3,141.9     3,094.5

Other assets                                            2,251.5     2,340.0

                                                     ----------  ----------
      Total Assets                                   $ 18,874.8  $ 18,691.2
                                                     ==========  ==========


LIABILITIES AND EQUITY                                     

Policy Liabilities
  Future policy benefits                             $    948.3  $    942.6
  Policy and contract claims                              790.1       809.4
  Unearned and advance premiums                         1,853.8     1,869.7
  Other policyholder funds                              1,011.1       828.1
                                                     ----------  ----------
      Total policy liabilities                          4,603.3     4,449.8


General Liabilities
  Insurance premiums payable                            6,538.1     6,379.8
  Commissions and general expenses                      1,382.3     1,488.8
  Short-term borrowings                                   675.6       764.2
  Notes payable                                           618.3       637.1
  Other liabilities                                     1,323.5     1,299.4
                                                     ----------  ----------
      Total Liabilities                                15,141.1    15,019.1


Commitments and Contingent Liabilities                                

Redeemable Preferred Stock                                 50.0        50.0

Company-obligated Mandatorily Redeemable
  Preferred Capital Securities of Subsidiary
  Trust holding solely the Company's Junior
  Subordinated Debentures                                 800.0       800.0

Stockholders' Equity
  Common stock - $1 par value                             171.5       171.5
  Paid-in additional capital                              393.8       377.0
  Net unrealized investment gains                         182.4       189.0
  Net foreign exchange losses                             (83.3)      (85.6)
  Retained earnings                                     2,506.9     2,463.4
  Less - Treasury stock at cost                           (77.0)      (93.2)
         Deferred compensation                           (210.6)     (200.0)
                                                     ----------  ----------
      Total Stockholders' Equity                        2,883.7     2,822.1

                                                     ----------  ----------
      Total Liabilities and Equity                   $ 18,874.8  $ 18,691.2
                                                     ==========  ==========

See the accompanying notes to the condensed consolidated financial statements.

                                          - 2 -                                



                                 Aon CORPORATION
                 CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
                                   (Unaudited)

                                                                                             First Quarter Ended
                                                                                       ----------------------------
                                                                                          March 31,       March 31,
(millions except per share data)                                                             1998            1997
                                                                                       ------------    ------------

REVENUE
                                                                                                         
   Brokerage commissions and fees ..............................................       $     996.2     $     841.7
   Premiums and other ..........................................................             416.8           394.4
   Investment income ...........................................................             148.5           118.2
                                                                                       ------------    ------------
      Total revenue ............................................................           1,561.5         1,354.3
                                                                                       ------------    ------------

EXPENSES
   General expenses ............................................................           1,048.2           943.0
   Benefits to policyholders ...................................................             225.9           205.2
   Interest expense ............................................................              20.1            14.6
   Amortization of intangible assets ...........................................              29.5            31.3
   Special charges .............................................................               --            145.0
                                                                                       ------------    ------------
      Total expenses ...........................................................           1,323.7         1,339.1
                                                                                       ------------    ------------

INCOME BEFORE INCOME TAX AND MINORITY INTEREST .................................             237.8            15.2
   Provision for income tax ....................................................              89.2             5.7
                                                                                       ------------    ------------
INCOME BEFORE MINORITY INTEREST ................................................             148.6             9.5
   Minority interest - 8.205% mandatorily redeemable preferred capital securities            (10.3)           (8.8)
                                                                                       ------------    ------------
NET INCOME .....................................................................       $     138.3     $       0.7
                                                                                       ============    ============
NET INCOME (LOSS) AVAILABLE FOR COMMON STOCKHOLDERS ............................       $     137.7     $      (2.7)
                                                                                       ============    ============

NET INCOME (LOSS) PER SHARE:
   Basic net income (loss) per share ...........................................       $      0.82    $      (0.02)
                                                                                       ============    ============

   Dilutive net income (loss) per share ........................................       $      0.80    $      (0.02)
                                                                                       ============    ============

CASH DIVIDENDS PAID ON COMMON STOCK ............................................       $      0.26    $       0.24
                                                                                       ============    ============

  Average common and common equivalent shares outstanding ......................             171.4           167.1
                                                                                       ------------    ------------

<FN>
See the accompanying notes to the condensed consolidated financial statements.
</FN>


                                          - 3 -                



                                 Aon CORPORATION
                 CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
                                   (Unaudited)


                                                                                     First Quarter Ended
                                                                             --------------------------------
                                                                                  March 31,       March 31,
(millions)                                                                           1998            1997
                                                                             ---------------   --------------

                                                                                                 
CASH PROVIDED BY OPERATING ACTIVITIES ...................................       $    256.2     $     307.8

CASH FLOWS FROM INVESTING ACTIVITIES:
  Sale of investments
         Short-term - net ...............................................              --             92.2
         Fixed maturities
               Maturities ...............................................             27.2            20.6
               Calls and prepayments ....................................             17.5            17.1
               Sales ....................................................          1,310.3           395.7
         Equity securities ..............................................          1,100.8           348.1
         Other investments ..............................................             33.0             1.6
  Purchase of investments
         Short-term - net ...............................................           (430.7)            --
         Fixed maturities ...............................................         (1,233.1)         (400.9)
         Equity securities ..............................................         (1,011.3)         (185.0)
         Other investments ..............................................            (39.8)          (13.7)
 Acquisition of subsidiaries ............................................            (96.1)       (1,289.8)
 Acquired fiduciary funds from acquisitions .............................              --            734.0
 Property and equipment and other .......................................            (42.7)          (28.6)
                                                                               ------------    ------------
               CASH USED BY INVESTING ACTIVITIES ........................           (364.9)         (308.7)
                                                                               ------------    ------------

CASH FLOWS FROM FINANCING ACTIVITIES:
   Treasury stock transactions - net ....................................             12.3            10.9
   Issuance (repayment) of short-term borrowings - net ..................            (88.7)          124.0
   Issuance of mandatorily redeemable preferred capital securities ......              --            800.0
   Repayment of long-term debt ..........................................            (19.0)          (51.1)
   Interest sensitive life, annuity and investment contracts
         Deposits .......................................................            186.5            37.0
         Withdrawals ....................................................            (18.1)            --
   Cash dividends to stockholders .......................................            (44.0)          (42.4)
                                                                               ------------    ------------
               Cash Provided by Financing Activities ....................             29.0           878.4
                                                                               ------------    ------------

EFFECT OF EXCHANGE RATE CHANGES ON CASH .................................              5.0           (18.0)
INCREASE (DECREASE) IN CASH .............................................            (74.7)          859.5
CASH AT BEGINNING OF PERIOD .............................................          1,084.7           410.1
                                                                               ------------    ------------
CASH AT END OF PERIOD ...................................................      $   1,010.0     $   1,269.6
                                                                               ------------    ------------
<FN>
See the accompanying notes to condensed consolidated financial statements.
</FN>


                                          - 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  generally  accepted  accounting  principles 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,  1997 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.

         Certain prior period amounts have been  reclassified  to conform to the
         current period presentation.


2.       Statements of Financial Accounting Standards (SFAS)
         ---------------------------------------------------

         Comprehensive Income
         --------------------

         As of January 1, 1998, Aon adopted the interim  reporting  requirements
         of  Financial  Accounting  Standards  Board  (FASB)  Statement  No. 130
         (Reporting Comprehensive Income) as presented below.  Statement No. 130
         establishes  new rules for the reporting and display  of  comprehensive
         income  and  its  components;  however the adoption  of this  Statement
         had no impact on Aon's  net  income or stockholders' equity.  Statement
         No.  130  requires  net  unrealized investment gains or losses on Aon's
         available-for-sale securities and net foreign exchange gains or losses,
         which currently are reported in  stockholders'  equity, to  be included
         in accumulated   other  comprehensive   income  and  the  disclosure of
         comprehensive  income. When Aon adopts the fiscal  year  end  reporting
         requirements  of  Statement  No. 130 in its December 31, 1998 financial
         statements,  the  totals  of  other   comprehensive  income  items  and
         comprehensive income (which includes net income),   will  be  displayed
         separately  and  prior  year financial statements will be  reclassified
         to  conform to the  requirements  of  Statement No. 130.

         The components of comprehensive income or loss, net of related tax, for
         the first quarter ended March 31, 1998 and 1997 are as follows:



(millions)                                                      1998                  1997
                                                                ----                  ----

                                                                                    
          Net income                                     $       138.3          $         0.7
          Net unrealized investment losses                        (6.6)                 (34.1)
          Net foreign exchange gains (losses)                      2.3                  (35.6)
                                                         ===================    ==================
          Comprehensive income (loss)                    $       134.0          $       (69.0)
                                                         ===================    ==================

                                          - 5 -

         The  components  of  accumulated  other  comprehensive  income,  net of
         related tax, at March 31, 1998 and December 31, 1997, are as follows:



(millions)                                                      1998                    1997
                                                                ----                    ----

                                                                                     
          Net unrealized investment gains                $       182.4           $       189.0
          Net foreign exchange losses                            (83.3)                  (85.6)
                                                         ====================    ===================
          Accumulated other comprehensive income         $        99.1           $       103.4
                                                         ====================    ===================




         Segments Disclosure
         -------------------

         In 1997, the FASB issued Statement No. 131 (Disclosures  about Segments
         of  an  Enterprise   and  Related   Information).   Statement  No.  131
         establishes standards for providing disclosures related to products and
         services,  geographic  areas, and major customers.  Aon will adopt this
         statement in its fourth quarter 1998 financial  statements as required.
         Implementation  of this  statement  is not  expected to have a material
         effect on Aon's financial statements.


3.       Capital Stock
         -------------

         In first quarter 1998, Aon reissued 436,500 shares of common stock from
         treasury for employee benefit plans. Aon purchased 18,200 shares of its
         common stock at a total cost of $1.1 million during first quarter 1998.
         In addition,  Aon reissued 210,900 shares of common stock from treasury
         in connection with business combinations. There were 2.9 million shares
         of common stock held in treasury at March 31, 1998.


4.       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.


5.       Business Combinations
         ---------------------

         In first quarter 1998, operating results were impacted by the insurance
         brokerage acquisition of Gil y Carvajal.  Gil y Carvajal is the largest
         retail and reinsurance  broker in Spain. This acquisition was accounted
         for by the  purchase  method.  The  effect of the  acquisition  was not
         material to Aon's consolidated financial statements.

         In April 1998, Aon acquired LeBlanc de Nicolay (the largest reinsurance
         broker in France),  subject to regulatory  approval.  This  acquisition
         will be  accounted  for by the  purchase  method  and its effect is not
         anticipated to be material to Aon's  consolidated financial statements.

                                           - 6 -

6.       Earnings Per Share
         ------------------

         Earnings per share is computed in  accordance  with FASB  Statement No.
         128 (Earnings Per Share) and is calculated as follows:



                                                                     First Quarter Ended
                                                      -------------------------------------------------
          (millions except per share data)              March 31, 1998               March 31, 1997
          ---------------------------------------------------------------------------------------------

                                                                                             
          Net income                                    $        138.3               $          0.7
          8% preferred stock dividends                              -                           2.8
          Redeemable preferred stock dividends                     0.6                          0.6
                                                        ===============              ===============
          Net income (loss) for dilutive and basic      $        137.7               $         (2.7)
                                                        ===============              ===============

          Basic shares outstanding                               168.7                        167.1
          Common stock equivalents                                 2.7                           -
                                                       ------------------------------------------------
          Dilutive potential common shares                       171.4                        167.1
          ---------------------------------------------------------------------------------------------
          Basic earnings per share                               $0.82                       ($0.02)
          Dilutive earnings per share                            $0.80                       ($0.02)
          ---------------------------------------------------------------------------------------------



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

         A&A discontinued its insurance underwriting operations in 1985, some of
         which were then placed into  run-off,  the  remainder  sold in 1987. In
         connection with those sales, A&A provided  indemnities to the purchaser
         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
         March  31,  1998,  the   liabilities   associated  with  the  foregoing
         indemnities and liabilities of insurance underwriting subsidiaries that
         are  currently in run-off  were  included in other  liabilities  in the
         accompanying condensed consolidated statement of financial position and
         amount  to  $152  million.  Such  liabilities  are  net of  reinsurance
         recoverables and other assets of $176 million.



8.       Contingencies
         -------------

         Aon and its  subsidiaries  are subject to numerous  claims and lawsuits
         that arise in the ordinary course of business.  Some of these cases are
         being  litigated in  jurisdictions  which have judicial  precedents and
         evidentiary  rules which are  generally  believed  to favor  individual
         plaintiffs  against  corporate  defendants.  The  damages  that  may be
         claimed in these and  other jurisdictions are substantial, including in
         many instances claims for punitive  or  extraordinary damages. Accruals
         for these lawsuits have  been  provided  to the extent that  losses are
         deemed  probable  and are estimable.

                                          - 7 -
 
         At the time of Aon's acquisition of A&A in January 1997, A&A was facing
         various  legal  claims,  several  of which  remain  ongoing.  While the
         possibility of substantial exposure remains, based on current facts and
         circumstances,  Aon believes the possibility of material loss resulting
         from these exposures is remote. 

         Although the ultimate outcome of these suits cannot be ascertained  and
         liabilities in  indeterminate  amounts may be  imposed  on  Aon  or its
         subsidiaries,  on the basis  of  present information,  availability  of
         insurance coverages and advice received from counsel, it is the opinion
         of management  that the disposition or ultimate  determination  of such
         claims and  lawsuits  will not have a  material adverse  effect on  the
         consolidated financial position of Aon.

                                           - 8 -

                                 Aon CORPORATION
                   MANAGEMENT'S ANALYSIS OF OPERATING RESULTS
                             AND FINANCIAL CONDITION

                      REVENUE AND INCOME BEFORE INCOME TAX
                             FOR FIRST QUARTER 1998


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

GENERAL
- - - - - - - - - - - - - - - - - -------
Certain amounts in the prior years' condensed  consolidated financial statements
have been reclassified to conform to the 1998 presentation.

Brokerage  commissions  and  fees  increased  $154.5  million  or 18.4% in first
quarter 1998,  primarily reflecting business combination activity related to the
acquisitions of Gil y Carvajal in first quarter 1998,  Jauch & Hubener in fourth
quarter 1997 and, to a lesser  extent,  Minet and certain  other 1997  brokerage
acquisitions.

Premiums and other is primarily  related to insurance  underwriting  operations.
Premiums and other  increased  $22.4 million or 5.7% in first  quarter  compared
with the same period last year.  Extended  warranty  premiums  earned  increased
$28.7 million or 24.4% in the quarter reflecting continued growth,  primarily in
the  appliance  and  electronic  lines.  There was modest growth in direct sales
business as a result of changes in the consumer  insurance market. The runoff of
North  American auto credit  business  partially  offset this growth in premiums
earned.

Investment  income,  which  includes  related  expenses and realized  investment
gains,  increased $30.3 million or 25.6% in the first quarter 1998 when compared
to prior year. Investment income growth was primarily related to income received
on  private  equity  and  other  investment  holdings.  Investment  income  from
insurance brokerage and consulting  operations,  primarily relating to fiduciary
funds,  increased to $44 million in first quarter 1998 from $39 million in 1997,
due to brokerage acquisition activity and internal growth.

Total  revenue  increased  $207.2  million or 15.3% in the first  quarter  1998,
primarily  attributable to brokerage acquisition activity and to income received
on private equity and other investment holdings.

Benefits to  policyholders  increased  10.1% or $20.7  million in first  quarter
1998, reflecting a higher volume of new extended warranty business.  This growth
was partially offset by the run-off of auto credit business as planned.

In first  quarter  1997,  Aon reported  special  charges of $145 million  ($90.6
million after-tax) related to the restructuring of Aon's brokerage operations as
a result of the acquisition of Alexander &  Alexander  Services  Inc. (A&A). The
special  charges  included  costs  related to severance  and other costs and the
consolidation of real estate space. The 1997 special charges were reflected as a
separate component of total expenses in the condensed consolidated statements of
operations.

Total  expenses  decreased  $15.4  million  or 1.2% in first  quarter  1998 when
compared to prior year.  The  decrease  reflects  the  inclusion  of 1997 pretax
special charges. In first quarter 1998,  restructuring  liabilities  related  to
1997 special charges have been reduced as planned, and reflect payments on those
special charges and valuation adjustments related to recent acquisitions.  Total
expenses,  excluding the 1997  special charges, increased  10.9% for  the  first
quarter 1998.  Income  before  income  tax increased  $222.6  million  or   over
                                          
                                          - 9 -


500% in first quarter 1998, when compared  to prior year, primarily  due  to the
inclusion of special  charges in first  quarter 1997. Excluding special charges,
income before income tax increased  48.4% when compared to first  quarter  1997,
largely  due to growth in the insurance   brokerage   and   consulting  services
segment and to the achievement of cost savings resulting  from the consolidation
of  brokerage operations.



MAJOR LINES OF BUSINESS
- - - - - - - - - - - - - - - - - -----------------------

GENERAL
- - - - - - - - - - - - - - - - - -------

For purposes of the following line of business discussions,  comparisons against
last year's results exclude special  charges.  Management  anticipates  that the
full  benefit of cost  savings  on  brokerage  operations  will  continue  to be
achieved  throughout  the remainder of 1998.  In addition,  references to income
before income tax exclude minority interest related to the capital securities.


INSURANCE BROKERAGE AND CONSULTING SERVICES
- - - - - - - - - - - - - - - - - -------------------------------------------

First quarter 1998 revenue and income before income tax have  been  impacted  by
the acquisition of Gil y Carvajal in first quarter 1998, and the acquisitions of
Jauch & Hubener, Minet and certain  other  brokerage  acquisitions in  third and
fourth quarter 1997.

Insurance and other  services  (retail,  reinsurance  and  wholesale  brokerage)
revenue  increased  $138.5  million  or 18.4% in the  first  quarter  1998  when
compared with the same period last year,  largely due to  acquisition  activity.
Insurance and other services  continued to reflect highly  competitive  property
and casualty pricing in the domestic market.

Consulting   provides  a  full  range  of  employee  benefits  and  compensation
consulting,   specialized   employee  assessment  and  training  programs,   and
administrative  services.  This business showed revenue growth of $21 million or
16.3% for the first quarter 1998 when  compared to prior year,  primarily due to
post-first  quarter  1997  acquisitions  and,  to  a  lesser  extent,  expanding
integrated human resources consulting programs.

Overall,  revenue for the insurance  brokerage and consulting  services  segment
increased $159.5 million or 18.1% in the first quarter 1998.  Acquisitions  made
in 1998 and  post-first  quarter  1997  accounted  for a  majority  of the above
mentioned  revenue growth in the quarter.  Excluding the impact of acquisitions,
revenue  related to brokerage core businesses  grew  approximately  4% in a very
competitive  environment.  Income before  income tax increased  $74.7 million or
68.8% when compared to first quarter 1997. The brokerage segment continues to be
impacted by a soft property and casualty market, particularly in the reinsurance
brokerage  business.  Pretax  margins in this  segment  improved for the quarter
reflecting cost savings resulting from the consolidation of businesses  acquired
in 1997.


U.S./INTERNATIONAL RESULTS
- - - - - - - - - - - - - - - - - --------------------------

First quarter international  insurance brokerage and consulting services revenue
represents 52% of the worldwide  total, and  international  income before income
tax represents 71% of the worldwide total.  International  brokerage  revenue of
$539.8 million increased 24.2% for the first quarter,  primarily  reflecting the

                                          - 10 -


acquisition  of  Jauch  &  Hubener in  late 1997  and  post-first  quarter  1997
acquisitions. International  brokerage  income before income tax increased 69.8%
for the first quarter  reflecting  the above  mentioned   acquisition  activity.
International brokerage  revenues for retail  brokerage services  generally  are
strongest during the first  quarter  of the year,  particularly  for continental
Europe,  while expenses are incurred on a more even basis throughout the year.


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

The insurance underwriting line of business primarily provides direct sales life
and accident and health products, and extended warranty products to individuals.
Revenue increased $29.6 million or 6.6% for the first quarter 1998 when compared
to prior year,  primarily  due to growth in the U.S.  extended  warranty  lines.
Direct sales business also continued to grow modestly.

Pretax income from insurance  underwriting decreased $0.3 million or 0.5% in the
first quarter 1998 when compared with last year reflecting start-up costs in the
worksite  marketing  initiative  and the  run-off of auto  credit  business  and
specialty  liability  programs.  Overall,  benefit and expense  margins in first
quarter 1998 did not suggest any significant shift in operating  trends.  Direct
sales accident & health business  improved its pretax margin in part due to good
domestic and  international  health product  sales.  Extended  warranty  profits
improved in the quarter, primarily due to a higher volume of new business in the
extended warranty mechanical line.

U.S./INTERNATIONAL RESULTS
- - - - - - - - - - - - - - - - - --------------------------

First  quarter  U.S.  insurance  underwriting  revenue  represents  71%  of  the
worldwide  total  and  U.S.  income  before  income  tax  represents  75% of the
worldwide total. U.S. insurance  underwriting income before income tax increased
2.3% in the quarter when compared to its 1997 level.  Results reflect the runoff
of the auto credit  business and  specialty  liability  programs.  International
insurance  underwriting  revenue of $138.1 million increased 5.8% in the quarter
principally  due to growth  in  premiums  earned,  primarily  in the  mechanical
extended  warranty  line.  International  pretax  income  decreased  7.9% in the
quarter, primarily due to unfavorable expense comparisons in the extended 
warranty  appliance and electronics  lines.  Measures are being
taken to reduce costs in these lines.

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

Revenue in this  category  consists  primarily of investment  income  (including
realized  investment gains) on capital.  Insurance company  investment income is
allocated  to the  underwriting  segment  based  on the  invested  assets  which
underlie policyholder liabilities. Excess invested assets and related investment
income,  which do not underlie these liabilities,  are reported in this segment.
Expenses include interest and other financing  expenses,  goodwill  amortization
associated with insurance brokerage and consulting  acquisitions,  and corporate
administrative costs.

Revenue  increased 64.2% or $18.1 million for the first quarter 1998,  primarily
due to higher levels of investment  income  received on private equity and other
investment  holdings.  The loss before income tax decreased  $3.2 million in the
quarter over the same period last year.  Revenue growth was partially  offset by
goodwill amortization related to acquisitions and interest expense on short-term
and long-term debt associated with acquisition financing.

                                          - 11 -



                                 Aon Corporation
                             MAJOR LINES OF BUSINESS



                                                                     First Quarter Ended
                                                        ---------------------------------------------
                                                           March 31,       March 31,        Percent
(millions)                                                    1998            1997           Change
                                                        ------------    ------------     ------------

REVENUE
- - - - - - - - - - - - - - - - - -------
Insurance brokerage and consulting services:
                                                                                         
    Insurance and other services .................      $     890.1     $     751.6            18.4 %
    Consulting ...................................            150.1           129.1            16.3
                                                        ------------    ------------     ------------
      Total revenue ..............................          1,040.2           880.7            18.1
                                                        ------------    ------------     ------------

Insurance underwriting:
     Direct sales - life, accident and health ....            257.7           254.7             1.2
     Extended warranty ...........................            159.4           129.4            23.2
     Other .......................................             57.9            61.3            (5.5)
                                                        ------------    ------------     ------------
      Total revenue ..............................            475.0           445.4             6.6
                                                        ------------    ------------     ------------

Corporate and other ..............................             46.3            28.2            64.2
                                                        ------------    ------------     ------------
      Total revenue ..............................      $   1,561.5     $   1,354.3            15.3 %
                                                        ============    ============     ============


INCOME BEFORE INCOME TAX
- - - - - - - - - - - - - - - - - ------------------------
Insurance brokerage and consulting services ......      $     183.3     $     108.6            68.8 %
      Special charges ............................              --           (145.0)            --
                                                        ------------    ------------     ------------
      Including special charges ..................            183.3           (36.4)            N/A

Insurance underwriting ...........................             64.5            64.8            (0.5)

Corporate and other ..............................            (10.0)          (13.2)            N/A
                                                        ------------    ------------     ------------
      Total income before income tax .............      $     237.8     $      15.2            +500 %
                                                        ============    ============     ============

                                          - 12 -

                        NET INCOME FOR FIRST QUARTER 1998


First  quarter  1998 net income was $138.3  million  ($0.80  dilutive per share)
compared to $0.7 million ($0.02 loss per share) in 1997.  First quarter 1997 net
income and the  related  loss per share  amount  were  primarily  influenced  by
after-tax  1997  special  charges of $90.6  million  ($0.54  per share)  with no
comparable  amount in first quarter  1998.  Basic net income per share was $0.82
and a loss of $0.02 in 1998 and 1997, respectively.

The effective tax rate was 37.5% for both 1998 and 1997. Dilutive average shares
outstanding  for  first  quarter  1998  increased  2.6%  when  compared  to 1997
primarily  due to the  reissuance  of common  shares from  treasury for employee
benefits.


                        CASH FLOW AND FINANCIAL POSITION
                        AT THE END OF FIRST QUARTER 1998


GENERAL
- - - - - - - - - - - - - - - - - -------

Cash flows from operating  activities in first quarter 1998 were $256.2 million,
a decrease of $51.6  million from first quarter  1997.  This decrease  primarily
reflects the timing of the  settlement  of  insurance  segment  receivables  and
payables,  and payments on special charges and valuation adjustments relating to
recent acquisitions.

Investing  activities  used cash of $364.9 million which was made available from
financing and operating  activities.  Cash used for acquisition  activity during
first quarter 1998 was $96.1  million,  primarily  reflecting the Gil y Carvajal
acquisition.

Cash totaling $29 million was provided  during first quarter 1998 from financing
activities.  The decrease of $849.4 million from first quarter 1997 is primarily
a result of the  1997  issuance of capital  securities.  Cash was  used  to  pay
dividends of $43.4 million on common stock and $0.6 million on redeemable 
preferred stock.

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  acquisition  financing.  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 in the long-term.

Due to the contractual  nature of its insurance  policyholder  liabilities which
are  intermediate  to long-term in nature,  Aon has invested  primarily in fixed
maturities.  With a carrying  value of $3 billion,  Aon's  total fixed  maturity
portfolio is invested  primarily in investment  grade holdings (96.6%) and has a
fair value which is 104.6% of amortized cost.

                                          - 13 -


Total assets  increased  $183.6  million to $18.9 billion since  year-end  1997.
Invested assets at  March 31, 1998 increased $195 million from year-end  levels,
primarily due to higher levels of short-term investments. The amortized cost and
fair value of less than investment  grade fixed maturity  investments,  at March
31, 1998, were $93.4 million and $97.1 million, respectively. The carrying value
of non-income  producing  investments  in Aon's  portfolio at March 31, 1998 was
$81.5 million, or 1.3% of total invested assets.

Aon uses derivative financial instruments  (primarily financial futures,  swaps,
options  and  foreign   exchange   forwards)  to:  (a)  hedge  foreign  currency
translation risk and other business risks (i.e.  interest rate and credit risk);
(b) hedge asset price risk associated with financial instruments whose change in
value is reported  under SFAS 115;  and (c) manage its  overall  asset/liability
duration  match.  As of  March  31,  1998,  Aon had  open  contracts, related to
the above, which  had unrealized gains of approximately $4.9 million.

Insurance brokerage  and consulting services receivables decreased $28.5 million
and insurance  premiums  payable  increased $158.3 million in first quarter 1998
when compared to year-end 1997.

Short-term  borrowings  decreased  at the end of  first  quarter  1998 by  $88.6
million when compared to year-end 1997.  Generally,  in the first quarter of the
year, cash flows to the parent company are larger due to the timing of dividends
received from the operating units. As a result, short-term borrowing levels tend
to decrease in the first quarter when  compared to the remaining  periods in the
year. Notes payable  decreased at the end of first quarter 1998 by $18.8 million
when compared to year-end  1997.  Included in notes payable at March 31, 1998 is
approximately  $31 million which  represents  the principal  amount of notes due
within one year.

Stockholders' equity increased $61.6 million in first quarter 1998 to $17.10 per
share,  an  increase  of $0.30 per share  since  year-end  1997.  This  increase
consisted of net income partially offset by net unrealized  investment losses of
$6.6 million and  dividends to common stockholders  of $90.4  million.  Included
in the reduction  for  dividends is  an accrual  for  the  second   quarter 1998
common stock dividend.


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

The condensed  consolidated  financial statements at March 31, 1998, and for the
first quarter then ended have been reviewed,  prior to filing,  by Ernst & Young
LLP, Aon's independent auditors, and their report is included herein.

                                       - 14 -

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 March 31,  1998,  and the related  condensed
consolidated statements of operations and cash flows for the three-month periods
ended March 31, 1998 and 1997. 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 generally accepted auditing  standards,  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  generally  accepted  accounting
principles.

We have  previously  audited,  in accordance  with generally  accepted  auditing
standards,  the consolidated  statement of financial position of Aon Corporation
as of December  31, 1997,  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 10, 1998, 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, 1997, 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
May 5, 1998

                                          - 15 -

                                     PART II
                                     -------

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


ITEM 4.           SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS

         (a)      The Annual Meeting of  Stockholders of the Registrant was held
                  on April 17, 1998 (the "1998 Annual Meeting").

         (b)      Not applicable.

         (c)(i)   Set forth below is the tabulation of the votes on each nominee
                  for election as a director:

                                                                        Withheld
                       Name                          For               Authority
                       ----                          ---               ---------

                     Daniel T. Carroll             150,119,262          544,390
                     Franklin A. Cole              150,208,040          455,612
                     Edgar D. Jannotta             150,171,091          492,561
                     Perry J. Lewis                150,184,822          478,830
                     Andrew J. McKenna             150,225,279          438,373
                     Newton N. Minow               148,700,286        1,963,366
                     Richard C. Notebaert          150,191,489          472,163
                     Donald S. Perkins             150,152,159          511,493
                     John W. Rogers, Jr.           150,244,847          418,805
                     Patrick G. Ryan               150,197,173          466,479
                     George A. Schaefer            150,229,715          433,937
                     Raymond I. Skilling           150,243,100          420,552
                     Fred L. Turner                150,244,969          418,683
                     Arnold R. Weber               150,229,422          434,230
                     Carolyn Y. Woo                150,166,879          496,773




         (ii)     Set forth below is the  tabulation of the vote on the adoption
                  of the Aon 1998 Employee Stock Purchase Plan.

                      For       Against           Abstain          Nonvote
                      ---       -------           -------          -------
                   144,677,432  5,722,501          263,719               0

                                          - 16 -

                                     PART II
                                     -------

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


         (iii)    Set forth below is the tabulation of the vote on the selection
                  of Ernst & Young LLP as auditors  for the  Registrant  for the
                  1998 fiscal year.

                     For        Against           Abstain          Nonvote
                     ---        -------           -------          -------
                  150,236,810   194,555           232,287               0

         (iv)     Set forth  below is the  tabulation  of the vote on a proposal
                  made by a stockholder  relating to certain  investments by the
                  Registrant   as  set  forth   beginning  on  page  25  of  the
                  Registrant's  Notice of Annual  Meeting  of  Holders of Common
                  Stock and Series C Preferred Stock and Proxy Statement for the
                  1998 Annual Meeting.

                     For         Against           Abstain         Nonvote
                     ---         -------           -------         -------
                   4,031,306   132,565,771        4,317,527       9,749,048

         (d)      Not applicable.


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 no Current Reports
                  -------------------
                  on Form 8-K during the quarter ended March 31, 1998.


                                    SIGNATURE

Pursuant to the  requirements  of the  Securities  and 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)

May 15, 1998                       /s/ Harvey N. Medvin
                                   --------------------
                                   HARVEY N. MEDVIN
                                   EXECUTIVE VICE PRESIDENT,
                                   CHIEF FINANCIAL OFFICER AND
                                   TREASURER
                                   (Principal Financial and Accounting Officer)


                                           - 17 -



                                 Aon CORPORATION

                                  EXHIBIT INDEX



Exhibit Number
In Regulation S-K
                                                                          Page
Item 601 Exhibit Table                                                     No.

(10)  Aon 1998 Employee Stock Purchase Plan

(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

(27) Financial Data Schedule

                                          - 18 -