SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549



                                    FORM 8-K


                                 CURRENT REPORT




     Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934



                     Date of Report (Date of earliest event
                                   reported):
                                January 31, 2003





                               AMEREN CORPORATION
             (Exact name of registrant as specified in its charter)




          Missouri                   1-14756                     43-1723446
(State or other jurisdiction       (Commission                (I.R.S. Employer
       of incorporation)           File Number)              Identification No.)




                 1901 Chouteau Avenue, St. Louis, Missouri 63103
              (Address of principal executive offices and Zip Code)






       Registrant's telephone number, including area code: (314) 621-3222






ITEM 2.  ACQUISITION OR DISPOSITION OF ASSETS

     On January 31, 2003, Ameren  Corporation  ("Ameren") issued a press release
announcing the closing of the  acquisition of all of the issued and  outstanding
common stock of CILCORP Inc. ("CILCORP"), an Illinois corporation,  from The AES
Corporation,  pursuant  to an  agreement  dated as of April 28, 2002 (the "Stock
Purchase  Agreement").  As of such  acquisition,  CILCORP  became a wholly-owned
subsidiary of Ameren.  CILCORP is the parent  company of Peoria,  Illinois-based
Central Illinois Light Company ("CILCO"). CILCO became an indirect subsidiary of
Ameren, but will remain a separate utility company, known as AmerenCILCO.

     Separately,  Ameren expects to close in February, 2003 its acquisition from
The AES Corporation of all of the issued and outstanding membership interests of
AES Medina Valley Cogen (No. 4), LLC ("Medina Valley"), pursuant to an agreement
dated as of April 28, 2002 (the "Membership Interest Purchase Agreement"). As of
such  acquisition,  Medina  Valley  will  become a  wholly-owned  subsidiary  of
AmerenEnergy  Resources  Company,  which is a direct  subsidiary  of Ameren that
holds its non  rate-regulated  operations.  Medina  Valley will become  known as
Ameren Medina Valley Cogen (No. 4), LLC.

     In a transaction valued at approximately  $1.4 billion,  Ameren will assume
approximately $900 million of CILCORP and Medina Valley debt and preferred stock
at  closing  and pay the  balance in cash for the stock of  CILCORP,  along with
certain  other  assets,  including  all of the  membership  interests  in Medina
Valley.  The transaction  includes  CILCO's  regulated  natural gas and electric
utility   businesses,   including   approximately  1,200  megawatts  of  largely
coal-fired  generating  capacity,   and  Medina  Valley's  indirectly  owned  40
megawatt, gas-fired electric generation plant.

     With this  acquisition,  Ameren ranks as Illinois'  second largest electric
utility based on the number of customers,  total assets and operating  revenues.
For more  information  regarding the  transaction,  please see the Press Release
filed  herewith as Exhibit 99.01 which is  incorporated  herein by reference and
the Stock Purchase Agreement and Membership Interest Purchase Agreement filed as
Exhibit 2.1 and Exhibit 2.2, respectively,  to Ameren's Quarterly Report on Form
10-Q filed for the period ended March 31, 2002.


ITEM 5.  OTHER EVENTS AND REGULATION FD DISCLOSURE

     In a  separate  press  release,  Ameren  announced  today two  Peoria-based
managers who will be the top operating officers at AmerenCILCO:  Scott A. Cisel,
49, vice president and chief operating  officer for  AmerenCILCO,  and Robert G.
Ferlmann,  41, vice president  trading and dispatch and unregulated  sales.  For
more  information  regarding  Mr. Cisel and Mr.  Ferlmann,  please see the Press
Release  filed  herewith  as  Exhibit  99.02  which is  incorporated  herein  by
reference.


ITEM 7.  FINANCIAL STATEMENTS AND EXHIBITS

(a)      Financial statements of businesses  acquired.  To be filed by amendment
         no later than 60 days after the date of this report.

(b)      Pro forma financial information. To be filed by amendment no later than
         60 days after the date of this report.



                                       2





ITEM 7.  FINANCIAL STATEMENTS AND EXHIBITS (CONT.)

(c)      Exhibits

         Exhibit No.         Description
         -----------         -----------

           99.01             Press Release, dated January 31, 2003.

           99.02             Press Release, dated January 31, 2003.



                                    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.

                                           AMEREN CORPORATION
                                              (Registrant)



                                           By    /s/ Martin J. Lyons
                                             ------------------------------
                                           Name:     Martin J. Lyons
                                           Title:      Controller
                                             (Principal Accounting Officer)


Date:  January 31, 2003







                                       3




                                                                   Exhibit 99.01

                                                                One Ameren Plaza
                                                            1901 Chouteau Avenue
                                                             St. Louis, MO 63103


[GRAPHIC OMITTED][GRAPHIC OMITTED]



Contacts:

Media:                 Analysts:             Investors:
Susan Gallagher        Bruce Steinke         Investor Services
(314) 554-2175         (314) 554-2574        invest@ameren.com


                      AMEREN COMPLETES PURCHASE OF CILCORP

St. Louis, Mo., Jan. 31,  2003---Ameren  Corporation (NYSE: AEE) today announced
that the company has acquired  CILCORP  Inc.,  from The AES  Corporation  (NYSE:
AES). CILCORP is the parent company of Peoria, Ill.-based Central Illinois Light
Co. (CILCO), which, beginning today, will operate as AmerenCILCO.

     In a transaction valued at approximately  $1.4 billion,  Ameren has assumed
CILCORP debt and preferred stock of approximately  $900 million and has paid the
balance in cash to  purchase  the common  stock of CILCORP,  along with  certain
other assets.  Announced in April, 2002, the purchase includes CILCORP's natural
gas and electric  businesses,  including 1,200  megawatts of largely  coal-fired
generating capacity.

     With this  acquisition,  Ameren ranks as Illinois'  second largest electric
utility based on the number of customers, total assets and operating revenues.

     "We are  extremely  pleased that this  acquisition  has been  approved in a
timely  manner  because this  acquisition  is a natural fit with our core energy
growth strategy," says Charles W. Mueller, chairman and chief executive officer,
Ameren  Corporation.   "This  brings  together  high  quality,  low-cost  energy
providers who have  customer-focused  philosophies  and solid positions in their
respective  markets.  AmerenCILCO's  operations  are in a service  territory and
market where we already operate very effectively. Synergies from the acquisition
are expected to make this transaction immediately accretive to earnings and will
drive strong long-term growth for our company."

     The  transaction,   unanimously  approved  by  both  companies'  boards  of
directors,  also gained the approval of the Illinois  Commerce  Commission,  the
Securities and Exchange Commission and the Federal Energy Regulatory  Commission
and the clearance  from the  Department  of Justice under the  Hart-Scott-Rodino
Antitrust Improvements Act.

     Key components of the transaction follow:

>>   The  headquarters  of  AmerenCILCO  will  remain in  Peoria,  where  Ameren
     anticipates  maintaining  the existing  operations  centers,  customer call
     center and other support functions.

>>   Staff  reductions   either  at  CILCORP  or  at  Ameren  that  result  from
     duplication  of functions  are expected to total less than 100,  will occur
     over the next year and are hoped to be achieved largely through  attrition.
     Existing labor contracts will be honored.

                                   -- more --



Add One

>>   Slated  for final  closing  in early  February  is a  provision  of the
     transaction  that  involves  the  assets  of  Medina  Valley  Cogen,  LLC-a
     40-megawatt,  gas-fired  electric  generation  plant.   The plant  produces
     electricity, steam and chilled water, which is sold to CILCO. CILCO resells
     plant output  to  Caterpillar-AmerenCILCO's  largest  industrial  customer.
     With the completion of this part of the transaction,  Medina Valley becomes
     an Ameren asset.

>>   Electric rates will remain frozen at current levels through 2006.

>>   Ameren  will  provide   annual  civic,   charitable   and  social   service
     contribution  levels of at least $1 million  to be used in the Peoria  area
     and other  locations now served by  AmerenCILCO.  That level will allow for
     continued  support of such activities and for the expansion of three Ameren
     community programs into the CILCO service territory.

>>   Ameren plans to commit  additional funds annually in continued  support for
     economic  development   organizations  and  to  support  special  marketing
     programs aimed at attracting new jobs to the Peoria area.

     "AmerenCILCO   and  Ameren's  other  utility   companies---AmerenCIPS   and
AmerenUE--will  continue a heritage of providing  strong  support to hundreds of
Illinois  communities  with a combined  customer base of nearly 600,000 electric
and nearly 400,000 natural gas customers in Illinois," said Mueller.

     With assets of more than $13  billion,  Ameren,  through its  subsidiaries,
serves 1.7 million  electric  customers  and 500,000  natural gas customers in a
49,000-square-mile area of Missouri and Illinois.

Safe Harbor Statement
- ---------------------

Statements made in this release,  which are not based on historical  facts,  are
"forward-looking"  and, accordingly,  involve risks and uncertainties that could
cause actual results to differ  materially from those  discussed.  Although such
"forward-looking"  statements  have  been  made in good  faith  and are based on
reasonable assumptions,  there is no assurance that the expected results will be
achieved.  These statements include (without limitation) statements as to future
expectations,  beliefs, plans, strategies,  objectives,  events, conditions, and
financial  performance.  In connection with the "safe harbor"  provisions of the
Private Securities  Litigation Reform Act of 1995, the company is providing this
cautionary  statement  to identify  important  factors  that could cause  actual
results to differ materially from those anticipated.

The following factors,  in addition to those discussed elsewhere in this release
and in past and  subsequent  securities  filings,  could cause results to differ
materially from management  expectations as suggested by such  "forward-looking"
statements:

o    the effects of the  stipulation  and  agreement  relating  to the  AmerenUE
     Missouri  excess  earnings  complaint  case and other  regulatory  actions,
     including changes in regulatory policy;
o    changes in laws and other  governmental  actions,  including  monetary  and
     fiscal policy;
o    the impact on the company of current regulations related to the opportunity
     for customers to choose alternative energy suppliers in Illinois;
o    the  effects of  increased  competition  in the future due to,  among other
     things,  deregulation of certain aspects of the company's  business at both
     the state and federal levels;

                                   -- more --



Add Two



o    the   effects   of   participation   in   a   Federal   Energy   Regulatory
     Commission-approved    regional   transmission   organization,    including
     activities associated with the Midwest Independent System Operator;
o    availability  and  future  market  prices  for  fuel and  purchased  power,
     electricity and natural gas,  including the use of financial and derivative
     instruments and volatility of changes in market prices;
o    average rates for electricity in the Midwest;
o    business and economic conditions;
o    the impact of the adoption of new accounting standards;
o    interest rates and the availability of capital;
o    actions of ratings agencies and the effects of such actions;
o    weather conditions;
o    generation plant construction, installation and performance;
o    operation of nuclear power facilities and decommissioning costs;
o    the  effects  of  strategic   initiatives,   including   acquisitions   and
     divestitures;
o    the impact of current environmental regulations on utilities and generating
     companies and the  expectation  that more  stringent  requirements  will be
     introduced over time,  which could  potentially  have a negative  financial
     effect;
o    future wages and employee benefits costs;
o    disruptions  of the capital  markets or other events  making the  company's
     access to necessary capital more difficult or costly;
o    competition from other generating  facilities including new facilities that
     may be developed in the future;
o    delays in receipt of regulatory  approvals for the  acquisition  of CILCORP
     Inc., the parent of Central Illinois Light Company ("CILCO"), or unexpected
     adverse conditions or terms of those approvals;
o    difficulties in integrating CILCO with the company's other businesses;
o    changes in the coal markets,  environmental  laws or regulations,  or other
     factors  adversely  impacting  synergy  assumptions in connection  with the
     CILCORP Inc. acquisition;
o    cost and availability of transmission  capacity for the energy generated by
     the Company's  generating  facilities  or required to satisfy  energy sales
     made by the Company; and
o    legal and administrative proceedings.

                                     # # #




                                                                   Exhibit 99.02

                                                                One Ameren Plaza
                                                            1901 Chouteau Avenue
                                                             St. Louis, MO 63103


[GRAPHIC OMITTED][GRAPHIC OMITTED]


Contacts:

Media:
Susan Gallagher        Leigh Morris          Neal Johnson
(314) 554-2175         (217) 535-5228        (309) 677-5516

                      AMEREN NAMES TWO OFFICERS TO SERVE AS
                     AMERENCILCO'S TOP MANAGEMENT IN PEORIA

St. Louis, Mo., Jan. 31,  2003---Ameren  Corporation (NYSE: AEE) today announced
two  Peoria-based  managers will be the top operating  officers at  AmerenCILCO:
Scott A. Cisel, 49, vice president and chief operating  officer for AmerenCILCO,
and Robert G. Ferlmann, 41, vice president, AmerenCILCO Trading and Dispatch and
Unregulated  Sales.  Ameren  Chairman  and Chief  Executive  Officer  Charles W.
Mueller  will be  chairman  of  AmerenCILCO,  and  Ameren  President  and  Chief
Operating Officer Gary Rainwater will serve as president of AmerenCILCO.

     Today,  the  company  announced  in a separate  release  the closing of the
transaction  to acquire  CILCORP Inc.,  from The AES  Corporation  (NYSE:  AES).
CILCORP is the parent company of Peoria,  Ill.-based  Central Illinois Light Co.
(CILCO),  which beginning today will operate as AmerenCILCO.  Announced in April
2002,  the purchase  includes  CILCORP's  natural gas and  electric  businesses,
including 1,200 megawatts of largely coal-fired generating capacity.

     Until his most  recent  appointment,  Scott  Cisel  served  as senior  vice
president at CILCO,  where he has been employed for 28 years. Cisel joined CILCO
as a summer meter reader and advanced  through various  management  positions in
sales,  customer  services  and  district  operations.  He was named  manager of
Commercial  Office  Operations  in 1981  and,  in the  1980s,  held a number  of
management positions in energy services,  rates, sales and customer service, and
research and development. He was promoted to director of Corporate Sales in 1993
and from 1995 to 1998,  served as vice  president,  at first  managing Sales and
Marketing,  then  Legislative and Public Affairs and later Sales,  Marketing and
Trading. In April 2001, he was named senior vice president.

     A trustee of Eureka  College,  Cisel serves on the board of the  Tri-County
Urban League,  in addition to many other civic  activities.  A native of Peoria,
Cisel  holds a  bachelor  of  science  degree  in  business  administration  and
economics from Culver Stockton  College and a master's degree in liberal studies
from Bradley University.

     Until his most recent  appointment,  Ferlmann  served as director of Energy
Trading  (both natural gas and  electricity)  for CILCO - a position he has held
since 1997.  Ferlmann joined CILCORP in 1987 as an accounting analyst and senior
accounting analyst and assumed progressively higher positions in Finance,  until
in 1993, he became senior energy supply administrator.

                                   -- more --



Add One

     Ferlmann holds a bachelor of science degree in accounting and a master's of
business administration degree - both from Bradley University. He is a certified
public  accountant  in  Illinois.  He serves on the board of  directors  for St.
Joseph Home and is an active member of the St. Thomas Parish Council.

     With assets of more than $13  billion,  Ameren,  through its  subsidiaries,
serves 1.7 million  electric  customers  and 500,000  natural gas customers in a
49,000-square-mile area of Missouri and Illinois.


                                      # # #