UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    Form 13F

                              Form 13F COVER PAGE

Report for the Calendar Year or Quarter Ended:  December 31, 2001

Check here if Amendment [ ]; Amendment Number:
This Amendment (Check only one.):      [ ]  is a restatement.
                                       [ ]  adds new holdings entries.

Institutional Investment Manager Filing this Report:

Name:      Aon Advisors, Inc.
Address:   200 East Randolph Street
           Chicago, IL 60601

Name of additional disclosed party:

Name:      Aon Corporation
Address:   200 East Randolph Street
           Chicago, IL 60601

Form 13F File Number:  28-2005
                       28-2401

The institutional investment manager filing this report and the person by whom
it is signed hereby represent that the person signing the report is authorized
to submit it, that all information contained herein is true, correct and
complete, and that it is understood that all required items, statements,
schedules, lists, and tables, are considered integral parts of this form.

Person Signing this Report on Behalf of Reporting Manager:

Name:   Michael A. Conway
Title:  President
Phone:  (312) 381-3330

Signature, Place, and Date of Signing:

/s/ Michael A. Conway             Chicago, IL                February 14, 2001
----------------------------      -----------------------    -----------------
[Signature]                       [City, State]              [Date]

Report Type (Check only one.):

[X] 13F HOLDINGS REPORT. (Check here if all holdings of this reporting manager
    are reported in this report.)

[ ] 13F NOTICE. (Check here if no holdings reported are in this report, and
    all holdings are reported by other reporting manager(s).)

[ ] 13F COMBINATION REPORT. (Check here if a portion of the holdings for this
    reporting manager are reported in this report and a portion are reported by
    other reporting manager(s).)



                             Form 13F SUMMARY PAGE

Report Summary


Number of Other Included Managers:         0

Form 13F Information Table Entry Total:    194

Form 13F Information Table Value Total:    $519,798
                                           (thousands)

List of Other Included Managers


Provide a numbered list of the name(s) and Form 13F file number(s) of all
institutional investment managers with respect to which this report is filed,
other than the manager filing this report.

[If there are no entries in this list, state "NONE" and omit the column headings
and list entries]

    No.        Form 13F File Number       Name

    NONE






                                                   FORM 13F INFORMATION TABLE

          NAME OF ISSUER        TITLE OF CLASS               CUSIP     MARKET VALUE  PAR SHARES  ITEM:6  ITEM:7  ITEM:8
                                                                                            
ACM GOVT OPPOR FUND INC.        Common Stock                 000918102    37,664,098   4,655,636    X               X
AOL TIME WARNER                 Common Stock                 00184A105     6,294,200     196,081    X               X
AT&T CORP.                      Common Stock                 001957109       295,708      16,301    X               X
AT&T CORP.                      Common Stock                 001957208       840,000      60,000    X               X
AT&T WIRELESS SERVICES          Common Stock                 00209A106       881,686      61,356    X               X
ABBOTT LABORATORIES             Common Stock                 002824100     1,672,500      30,000    X               X
ALCOA, INC.                     Common Stock                 013817101     2,133,000      60,000    X               X
ALLIED WASTE INDUSTRIES INC     Common Stock                 019589308     1,617,153     115,018    X               X
ALLTEL CORP.                    Common Stock                 020039103     2,777,850      45,000    X               X
AMERICAN HOME PRODUCTS          Common Stock                 026609107       736,320      12,000    X               X
AMERICAN INTERNATIONAL GROUP    Common Stock                 026874107     8,564,241     107,862    X               X
AMETEK INC                      Common Stock                 031100100       542,130      17,000    X               X
AMGEN, INC.                     Common Stock                 031162100     3,837,920      68,000    X               X
ANADARKO PETROLEUM CORP         Common Stock                 032511107     2,728,800      48,000    X               X
ANDREW CORPORATION              Common Stock                 034425108     1,860,650      85,000    X               X
ANHEUSER-BUSCH COMPANIES INC    Common Stock                 035229103     3,390,750      75,000    X               X
AON FUNDS                       Common Stock                 036912889   150,168,599  14,751,336    X               X
APACHE CORP.                    Common Stock                 037411105     3,182,344      63,800    X               X
BP AMOCO PLC                    Common Stock                 055622104     2,930,130      63,000    X               X
BANKAMERICA CORP                Common Stock                 060505104     2,455,050      39,000    X               X
BIOGEN                          Common Stock                 090597105     2,179,300      38,000    X               X
BRISTOL MYERS SQUIBB            Common Stock                 110122108     2,958,000      58,000    X               X
BURLINGTON NORTHERN/SANTA FE    Common Stock                 12189T104     1,369,440      48,000    X               X
CSX CORPORATION                 Common Stock                 126408103     2,453,500      70,000    X               X
CVS CORPORATION                 Common Stock                 126650100     2,634,400      89,000    X               X
CARDINAL HEALTH INC.            Common Stock                 14149Y108     3,717,950      57,500    X               X
CARNIVAL CORP                   Common Stock                 143658102     1,684,800      60,000    X               X
CHEVRONTEXACO CORP              Common Stock                 166764100     2,069,991      23,100    X               X
CINAR CORP CL B SUB VTG         Common Stock                 171905300        90,000      40,000    X               X
CISCO SYSTEMS                   Common Stock                 17275R102     1,159,040      64,000    X               X
CITIGROUP INC.                  Common Stock                 172967101     5,104,184     101,113    X               X
CITRIX SYSTEMS INC              Common Stock                 177376100     1,133,000      50,000    X               X
CLEAR CHANNEL COMM              Common Stock                 184502102     4,296,448      84,393    X               X
COCA COLA CO                    Common Stock                 191216100     3,064,750      65,000    X               X
COLGATE PALMOLIVE CO            Common Stock                 194162103     2,385,075      41,300    X               X
COMPAQ COMPUTER                 Common Stock                 204493100       634,400      65,000    X               X
COMVERSE TECHNOLOGY,INC         Common Stock                 205862402       335,550      15,000    X               X
CONCORD EFS INC                 Common Stock                 206197105       983,400      30,000    X               X
CONSECO CONVERTIBLE SEC. FUND   Common Stock                 20846T672       992,388     103,159    X               X
CORNING INC.                    Common Stock                 219350105       490,600      55,000    X               X
DRS TECHNOLOGIES, INC.          Common Stock                 23330X100        35,650       1,000    X               X
DEAN FOODS                      Common Stock                 242370104       892,363      13,085    X               X
DEERE & CO                      Common Stock                 244199105     2,095,680      48,000    X               X
DELL COMPUTER CORP              Common Stock                 247025109     3,036,006     111,700    X               X
DEVON ENERGY                    Common Stock                 25179M103     1,932,500      50,000    X               X
DIGITAL RIVER INC               Common Stock                 25388B104       477,600      30,000    X               X
THE WALT DISNEY CO.             Common Stock                 254687106     2,072,000     100,000    X               X
DIVINE INTERVENTURES            Common Stock                 255402109     1,644,445   2,222,223    X               X
DOW CHEMICAL                    Common Stock                 260543103     1,790,340      53,000    X               X
DUPONT (E.I.) DENEMOURS & CO    Common Stock                 263534109     2,125,500      50,000    X               X
DUKE REALTY CORP.               Common Stock                 264411505       878,315      36,100    X               X
EMC CORP./MASS                  Common Stock                 268648102     1,076,705      80,112    X               X
EASTMAN CHEMICAL                Common Stock                 277432100     2,536,300      65,000    X               X
ECOMETRY CORP                   Common Stock                 27900H106        78,300      30,000    X               X
EMERSON ELECTRIC CO.            Common Stock                 291011104     3,254,700      57,000    X               X
ENGINEERED SUPPORT SYSTEMS INC  Common Stock                 292866100       410,520      12,000    X               X
EQUITY OFFICE PROPERTIES TRUST  Common Stock                 294741103       582,753      19,373    X               X
EXXON MOBIL CORP                Common Stock                 30231G102     6,712,676     170,806    X               X
FEDERAL HOME LOAN MTGE CORP     Common Stock                 313400301     1,033,320      15,800    X               X
FEDERAL NATIONAL MORTGAGE ASSN  Common Stock                 313586109     5,779,650      72,700    X               X
FIBERMARK INC                   Common Stock                 315646109       274,560      48,000    X               X
FIRST DATA CORPORATION          Common Stock                 319963104     1,622,111      20,677    X               X
FIRST FEDERAL SAVINGS BANK      Common Stock                 33761K105     1,629,269      57,167    X               X
FORD MOTOR COMPANY              Common Stock                 345370860     3,572,559     227,262    X               X
FOUNDRY NETWORKS IN             Common Stock                 35063R100       114,100      14,000    X               X
FOX ENTERTAINMENT GRP INC-A     Common Stock                 35138T107       583,660      22,000    X               X
GENERAL ELECTRIC                Common Stock                 369604103     6,738,891     168,136    X               X
GENTEX CORP                     Common Stock                 371901109       668,250      25,000    X               X
GEORGIA-PACIFIC CORP            Common Stock                 373298108     2,070,750      75,000    X               X
W.W. GRAINGER INC.              Common Stock                 384802104     2,280,000      47,500    X               X
HCA INC                         Common Stock                 404119109     1,541,600      40,000    X               X
HRPT PROPERTIES, INC            Common Stock                 40426W101     1,751,918     202,300    X               X
JOHN HANCOCK FINANCIAL SVCS     Common Stock                 41014S106       158,964       3,849    X               X
HARTMARX                        Common Stock                 417119104       166,815     101,100    X               X
HELMERICH AND PAYNE INC.        Common Stock                 423452101       340,476      10,200    X               X
HEWLETT PACKARD CO.             Common Stock                 428236103     1,499,420      73,000    X               X
HOME DEPOT INC                  Common Stock                 437076102     2,808,662      55,061    X               X
HONEYWELL INTERNATIONAL INC.    Common Stock                 438516106     1,521,900      45,000    X               X
HOTJOBS.COM LTD                 Common Stock                 441474103        51,950       5,000    X               X
ILLINOIS TOOL WORKS INC.        Common Stock                 452308109     2,708,800      40,000    X               X
IMAGISTICS INTL INC             Common Stock                 45247T104        17,784       1,440    X               X
INTEL CORPORATION               Common Stock                 458140100     2,704,700      86,000    X               X
INT'L BUSINESS MACHINES         Common Stock                 459200101     6,048,000      50,000    X               X
INTERNATIONAL PAPER COMPANY     Common Stock                 460146103       847,350      21,000    X               X
IVEX PACKAGING                  Common Stock                 465855104     1,041,200      54,800    X               X
JP MORGAN CHASE & CO            Common Stock                 46625H100       508,900      14,000    X               X
JOHNSON & JOHNSON               Common Stock                 478160104     7,566,691     128,032    X               X
KELLOGG CO.                     Common Stock                 487836108       963,200      32,000    X               X
KROGER                          Common Stock                 501044101     1,969,460      94,368    X               X
L-3 COMMUNICATIONS HLDGS INC    Common Stock                 502424104     2,628,000      29,200    X               X
ELI LILLY & CO.                 Common Stock                 532457108     2,748,900      35,000    X               X
LITTELFUSE, INC.                Common Stock                 537008104     1,049,600      40,000    X               X
MGIC INVESTMENT CORP            Common Stock                 552848103     1,543,000      25,000    X               X
MSC INDUSTRIAL DIRECT           Common Stock                 553530106       197,500      10,000    X               X
MATRIXONE INC                   Common Stock                 57685P304     1,356,208     104,404    X               X
MAY DEPT STORES                 Common Stock                 577778103     2,329,740      63,000    X               X
MCDONALDS CORP                  Common Stock                 580135101     1,402,910      53,000    X               X
MEDIMMUNE INC                   Common Stock                 584699102     1,854,000      40,000    X               X
MERCK & CO.                     Common Stock                 589331107     2,940,000      50,000    X               X
METALS USA INC                  Common Stock                 591324108         1,200      20,000    X               X
MICROSOFT CORP.                 Common Stock                 594918104     5,697,500      86,000    X               X
MOBILE MINI INC                 Common Stock                 60740F105     2,190,720      56,000    X               X
MORGAN STANLEY DEAN WITTER & C  Common Stock                 617446448     2,125,754      38,001    X               X
NANOPHASE TECHNOLOGIES          Common Stock                 630079101       340,442      57,800    X               X
NASDAQ 100 SHARES               Common Stock                 631100104     2,361,565      60,693    X               X
NEWPARK RESOURCES INC.          Common Stock                 651718504       985,004     124,684    X               X
NEWS CORP LTD-SPONS ADR         Common Stock                 652487703       922,490      29,000    X               X
NOKIA ADR A                     Common Stock                 654902204     1,815,220      74,000    X               X
NORFOLK SOUTHERN CORP           Common Stock                 655844108     1,919,151     104,700    X               X
NORTHSTAR CAPITAL INVMNT GRP    Common Stock                 66704F999     1,072,380      53,619    X               X
NUCOR CORP                      Common Stock                 670346105     1,165,120      22,000    X               X
OMEGA WORLDWIDE INC             Common Stock                 68210B108        32,601      20,000    X               X
PAXSON COMMUNICATION            Common Stock                 704231109       209,000      20,000    X               X
PEPSICO INC                     Common Stock                 713448108     1,217,250      25,000    X               X
PETROLEUM GEO-SVCS -SPON ADR    Common Stock                 716597109       756,200      95,000    X               X
PFIZER, INC.                    Common Stock                 717081103     6,555,325     164,500    X               X
PITNEY BOWES INC                Common Stock                 724479100     1,241,130      33,000    X               X
BANCO POPULAR                   Common Stock                 733174106        76,791       2,641    X               X
POWERWAVE TECHNOLOGIES INC      Common Stock                 739363109     1,572,480      91,000    X               X
PRICE LEGACY CORPORATION        Common Stock                 74144P106       141,154      44,669    X               X
PUBLIC STORAGE INC.             Common Stock                 74460D109            23           1    X               X
QUANTA SERVICES INC             Common Stock                 74762E102     1,033,810      67,000    X               X
RADIANT SYSTEMS INC             Common Stock                 75025N102       437,000      38,000    X               X
RADIOSHACK CORP                 Common Stock                 750438103     1,053,500      35,000    X               X
RAILWORKS CORP                  Common Stock                 750789109         9,300      60,000    X               X
RIO ALTO EXPLORATION LTD        Common Stock                 766892103       935,350      80,000    X               X
ROYAL DUTCH PETROLEUM CO.       Common Stock                 780257804     1,519,620      31,000    X               X
SPX CORPORATION                 Common Stock                 784635104     2,738,000      20,000    X               X
SAKS INCORPORATED               Common Stock                 79377W108       579,080      62,000    X               X
SANDISK CORP                    Common Stock                 80004C101       331,200      23,000    X               X
SCHERING PLOUGH CORP            Common Stock                 806605101     4,540,994     126,808    X               X
SCHOLASTIC CORP                 Common Stock                 807066105     2,516,500      50,000    X               X
SHELL TRANSPORT - TRADING ADR   Common Stock                 822703609       829,000      20,000    X               X
SHIRE PHARMACEUTICALS           Common Stock                 82481R106       805,200      22,000    X               X
SIGMA ALDRICH                   Common Stock                 826552101       236,460       6,000    X               X
SIX FLAGS INC.                  Common Stock                 83001P109     1,076,600      70,000    X               X
SPRINT CORPORATION              Common Stock                 852061100       903,600      45,000    X               X
STATE STREET CORP               Common Stock                 857477103     1,567,500      30,000    X               X
SUN MICROSYSTEMS, INC.          Common Stock                 866810104     1,586,700     129,000    X               X
SUNGARD DATA SYSTEMS            Common Stock                 867363103     2,314,400      80,000    X               X
SYMANTEC CORP                   Common Stock                 871503108       994,950      15,000    X               X
TARGET CORP                     Common Stock                 87612E106     2,052,500      50,000    X               X
TECHNITROL INC                  Common Stock                 878555101     1,104,800      40,000    X               X
TELLABS INC.                    Common Stock                 879664100     1,563,320     104,500    X               X
TENET HEALTHCARE CORP           Common Stock                 88033G100     2,642,400      45,000    X               X
TEXAS INSTRUMENTS               Common Stock                 882508104       868,000      31,000    X               X
TEXTRON, INC                    Common Stock                 883203101     2,073,000      50,000    X               X
TRIBUNE CO                      Common Stock                 896047107     3,518,420      94,000    X               X
TROPICAL SPORTSWEAR INTL        Common Stock                 89708P102       309,375      16,500    X               X
U.S. AIRWAYS GROUP, INC.        Common Stock                 911905107       124,226      19,594    X               X
VF CORP.                        Common Stock                 918204108     1,755,450      45,000    X               X
VERIZON CORPORATION             Common Stock                 92343V104     1,661,100      35,000    X               X
VIACOM INC                      Common Stock                 925524100     1,327,500      30,000    X               X
VIACOM INC                      Common Stock                 925524308       522,736      11,840    X               X
VOICESTREAM WIRELESS CORP       Common Stock                 928615103           982          11    X               X
WACHOVIA CORP. 2ND NEW COM      Common Stock                 929903102     2,352,000      75,000    X               X
WAL-MART STORES, INC.           Common Stock                 931142103     1,035,900      18,000    X               X
WALGREENS CO                    Common Stock                 931422109     4,039,200     120,000    X               X
WATSCO                          Common Stock                 942622101       169,200      12,000    X               X
WATSCO                          Common Stock                 942622200     1,704,000     120,000    X               X
WATSON PHARMACEUTICALS, INC.    Common Stock                 942683103       627,800      20,000    X               X
WILLAMETTE INDUSTRIES           Common Stock                 969133107     2,501,760      48,000    X               X
WINTRUST FINANCIAL CORP         Common Stock                 97650W108     1,427,619      46,700    X               X
WIRELESS TELECOM GROUP, INC.    Common Stock                 976524108       310,168     109,600    X               X
WORLDCOM INC                    Common Stock                 98157D106     1,430,528     101,600    X               X
WORLDCOM INC                    Common Stock                 98157D304        51,613       4,064    X               X
WRIGLEY, (WM) JR. CO.           Common Stock                 982526105     1,181,510      23,000    X               X
YAHOO ! INC.                    Common Stock                 984332106     1,312,760      74,000    X               X
YOUNG BROADCASTING CORP -A      Common Stock                 987434107     1,175,725      65,500    X               X
ZIMMER HOLDINGS INC             Common Stock                 98956P102       152,700       5,000    X               X
MAX RE CAPITAL LTD.             Common Stock                 G6052F103     7,308,000     466,667    X               X
TRENWICK GROUP                  Common Stock                 G9032C109     6,789,817     667,632    X               X
AUDIOCODES LTD                  Common Stock                 M15342104       282,500      50,000    X               X
SUN INTERNATIONAL HOTELS LTD-A  Common Stock                 P8797T133       399,972      15,778    X               X
CKE RESTAURANTS INC             Taxable Bonds-Convertible    12561EAB1       851,363   1,095,000    X               X
CLEAR CHANNEL COMM              Taxable Bonds-Convertible    184502AE2       414,906     425,000    X               X
ESC MEDICAL SYSTEMS             Taxable Bonds-Convertible    269025AA0       513,663     545,000    X               X
ESC MEDICAL SYSTEMS             Taxable Bonds-Convertible    269025AB8       301,600     320,000    X               X
GETTY IMAGES, INC               Taxable Bonds-Convertible    374276AA1     1,502,400   2,000,000    X               X
GETTY IMAGES, INC               Taxable Bonds-Convertible    374276AD5     4,935,000   6,000,000    X               X
GOLD EAGLE CAPITAL 2001         Taxable Bonds-Convertible    38058MAA0     4,024,720   4,000,000    X               X
HEALTHSOUTH CORP                Taxable Bonds-Convertible    421924AD3     1,385,175   1,460,000    X               X
HILTON HOTELS CORP.             Taxable Bonds-Convertible    432848AL3       597,375     675,000    X               X
INTERIM SERVICES, INC.          Taxable Bonds-Convertible    45868PAA8       918,125   1,130,000    X               X
KELLSTROM INDUSTRIES            Taxable Bonds-Convertible    488035AC0       175,000   3,500,000    X               X
KELLSTROM INDUSTRIES            Taxable Bonds-Convertible    488035AE6       100,000   2,000,000    X               X
KERR MCGEE CORP                 Taxable Bonds-Convertible    492386AP2     1,280,813   1,150,000    X               X
MASCOTECH INC.                  Taxable Bonds-Convertible    574670AB1       722,275     865,000    X               X
MUTUAL RISK                     Taxable Bonds-Convertible    628351AA6       390,000   1,000,000    X               X
QUANTA SERVICES INC             Taxable Bonds-Convertible    74762EAA0     1,335,000   2,000,000    X               X
THERMO INSTRUMENT SYSTEMS       Taxable Bonds-Convertible    883559AE6       642,875     695,000    X               X
THERMO FIBERTEK INC             Taxable Bonds-Convertible    88355WAA3       472,500     500,000    X               X
THERMO FIBERTEK INC             Taxable Bonds-Convertible    VV3081948       475,000     500,000    X               X
BOLDER TECHNOLOGIES CORP.       Preferred Stock-Convertible  097519912     2,000,000      40,000    X               X