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 22, 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


<PAGE>



ITEM 5. OTHER EVENTS AND REGULATION FD DISCLOSURE

     On January 22, 2003, the Registrant issued a press release  announcing that
the U.S.  Department  of Justice has  completed  its review of the  Registrant's
proposed  acquisition  of  CILCORP  Inc.  from  The AES  Corporation  under  the
Hart-Scott-Rodino  Antitrust Improvements Act. The press release states that the
transaction  has  received   regulatory  approval  from  the  Illinois  Commerce
Commission and the Federal Energy Regulatory  Commission  leaving the Securities
and Exchange  Commission the only remaining  regulatory  approval required.  The
press release is attached as Exhibit 99 and is incorporated herein by reference.


ITEM 7. EXHIBITS

        (c) Exhibits.

            99 Press release, dated January 22, 2003, issued by the
               Registrant.



                                    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 22, 2003




                                      2

<PAGE>



                                  Exhibit Index
                                  -------------


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

    99     - Press release dated January 22, 2003, issued by Ameren Corporation.








                                       3


<PAGE>


[GRAPHIC OMITTED][GRAPHIC OMITTED]
                                                                One Ameren Plaza
                                                            1901 Chouteau Avenue
                                                             St. Louis, MO 63103

Contact:

Analysts:                Media:
Bruce Steinke            Susan Gallagher
(314) 554-2574           (314) 554-2175

FOR IMMEDIATE RELEASE
---------------------

                         DEPARTMENT OF JUSTICE COMPLETES
               REVIEW OF AMEREN'S PROPOSED ACQUISITION OF CILCORP

ST. LOUIS, MO, Jan. 22, 2003-Ameren Corporation (NYSE: AEE) announced today that
the U.S.  Department  of Justice  (DOJ) has completed its review of the proposed
Ameren  acquisition of CILCORP Inc. from The AES  Corporation  (NYSE:  AES).

     The review,  conducted under the Hart-Scott-Rodino  Antitrust  Improvements
Act pertaining to the pending sale of CILCORP, began last summer.

     The  completion  of the  review  paves  the  way  for  the  closing  of the
transaction early in the first quarter of 2003, with the Securities and Exchange
Commission the only remaining regulatory approval required.

     The transaction has received regulatory approval from the Illinois Commerce
Commission (ICC) and the Federal Energy Regulatory Commission (FERC).

     Ameren's  agreement  to purchase  CILCORP  was  announced  April 29,  2002.
Regulatory  approval came from the ICC on Dec. 4, 2002 and from the FERC on Nov.
20, 2002.

     With assets of $10 billion and 2001 revenues of $4.5 billion, Ameren serves
1.5  million  electric   customers  and  300,000  natural  gas  customers  in  a
44,500-square-mile  area of Missouri and  Illinois.  With $1.8 billion in assets
and 2001 revenues of $815 million,  CILCORP's largest subsidiary,  CILCO, serves
200,000 electric and more than 200,000 natural gas customers.


Safe Harbor Statement
---------------------
     This news release may include forward-looking statements. Actual events and
results may differ  materially from those  projected.  Factors that could affect
actual  results  are  discussed  in Ameren's  filings  with the  Securities  and
Exchange  Commission,  and readers are encouraged to read those filings to learn
more about the risk factors associated with Ameren's businesses.

                                      # # #
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{"company-data": {"conformed-name": "AMEREN CORP", "cik": "0001002910", "assigned-sic": "4931", "irs-number": "431723446", "state-of-incorporation": "MO", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "001-14756", "film-number": "03520612"}, "business-address": {"street1": "1901 CHOUTEAU AVE", "street2": "MC 1370", "city": "ST LOUIS", "state": "MO", "zip": "63166-6149", "phone": "431723446"}, "mail-address": {"street1": "1901 CHOUTEAU AVE", "street2": "MC 1370", "city": "ST LOUIS", "state": "MO", "zip": "63103"}}
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 22, 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 5. OTHER EVENTS AND REGULATION FD DISCLOSURE

     On January 22, 2003, the Registrant issued a press release  announcing that
the U.S.  Department  of Justice has  completed  its review of the  Registrant's
proposed  acquisition  of  CILCORP  Inc.  from  The AES  Corporation  under  the
Hart-Scott-Rodino  Antitrust Improvements Act. The press release states that the
transaction  has  received   regulatory  approval  from  the  Illinois  Commerce
Commission and the Federal Energy Regulatory  Commission  leaving the Securities
and Exchange  Commission the only remaining  regulatory  approval required.  The
press release is attached as Exhibit 99 and is incorporated herein by reference.

ITEM 7. EXHIBITS

        (c) Exhibits.

            99 Press release, dated January 22, 2003, issued by the
               Registrant.

                                    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 22, 2003

                                      2
Exhibit Index
                                  -------------

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

    99     - Press release dated January 22, 2003, issued by Ameren Corporation.

                                       3
[GRAPHIC OMITTED][GRAPHIC OMITTED]
                                                                One Ameren Plaza
                                                            1901 Chouteau Avenue
                                                             St. Louis, MO 63103

Contact:

Analysts:                Media:
Bruce Steinke            Susan Gallagher
(314) 554-2574           (314) 554-2175

FOR IMMEDIATE RELEASE
---------------------

                         DEPARTMENT OF JUSTICE COMPLETES
               REVIEW OF AMEREN'S PROPOSED ACQUISITION OF CILCORP

ST. LOUIS, MO, Jan. 22, 2003-Ameren Corporation (NYSE: AEE) announced today that
the U.S.  Department  of Justice  (DOJ) has completed its review of the proposed
Ameren  acquisition of CILCORP Inc. from The AES  Corporation  (NYSE:  AES).

     The review,  conducted under the Hart-Scott-Rodino  Antitrust  Improvements
Act pertaining to the pending sale of CILCORP, began last summer.

     The  completion  of the  review  paves  the  way  for  the  closing  of the
transaction early in the first quarter of 2003, with the Securities and Exchange
Commission the only remaining regulatory approval required.

     The transaction has received regulatory approval from the Illinois Commerce
Commission (ICC) and the Federal Energy Regulatory Commission (FERC).

     Ameren's  agreement  to purchase  CILCORP  was  announced  April 29,  2002.
Regulatory  approval came from the ICC on Dec. 4, 2002 and from the FERC on Nov.
20, 2002.

     With assets of $10 billion and 2001 revenues of $4.5 billion, Ameren serves
1.5  million  electric   customers  and  300,000  natural  gas  customers  in  a
44,500-square-mile  area of Missouri and  Illinois.  With $1.8 billion in assets
and 2001 revenues of $815 million,  CILCORP's largest subsidiary,  CILCO, serves
200,000 electric and more than 200,000 natural gas customers.

Safe Harbor Statement
---------------------
     This news release may include forward-looking statements. Actual events and
results may differ  materially from those  projected.  Factors that could affect
actual  results  are  discussed  in Ameren's  filings  with the  Securities  and
Exchange  Commission,  and readers are encouraged to read those filings to learn
more about the risk factors associated with Ameren's businesses.

                                      # # #