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):
                                 October 3, 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


     Reference is made to Item 2.  Properties  under Part I in the  Registrant's
Form 10-K for the year ended  December 31, 2002 for a discussion  of the plan of
the Registrant's  subsidiary,  Central Illinois Light Company, which operates as
AmerenCILCO,  to transfer substantially all of its electric generation assets to
its non-rate regulated subsidiary, Central Illinois Generation, Inc., whose name
has been changed to AmerenEnergy Resources Generating Company (AERG).

     On  October  3,  2003,  AmerenCILCO  transferred  its Duck  Creek and E. D.
Edwards  coal-fired plants and its Sterling Avenue combustion turbine facilities
representing  approximately 1,100 megawatts of generating capacity,  all located
in  Illinois,  to AERG as a  contribution  in respect of all of the  outstanding
stock of AERG and AERG's assumption of certain  liabilities.  The net book value
of the transferred  assets was  approximately  $380 million as of June 30, 2003.
Approximately 23% of AmerenCILCO's  employees were transferred to AERG as a part
of the transaction.

     Also on  October  3, 2003,  AERG  entered  into an  electric  power  supply
agreement with AmerenCILCO to supply it sufficient power to meet its native load
requirements.  This agreement  expires  December 31, 2004.  AERG and AmerenCILCO
plan to pursue an  extension  of the electric  power  supply  agreement  through
December 31, 2006. The Illinois Commerce Commission authorized this extension in
its order approving the Registrant's acquisition of AmerenCILCO.


     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

                                    By    /s/ Martin J. Lyons
                                               Martin J. Lyons
                                         Vice President and Controller
                                        (Principal Accounting Officer)

Date:  October 3, 2003