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):
                                December 5, 2003
<TABLE>
<CAPTION>


                               Exact Name of Registrant as specified in its charter;
         Commission            State of Incorporation;                                         IRS Employer
         File Number           Address and Telephone Number                                    Identification No.
         -----------           ----------------------------                                    ------------------
        <S>                   <C>                                                                  <C>
         1-14756               Ameren Corporation                                                   43-1723446
                               (Missouri Corporation)
                               1901 Chouteau Avenue
                               St. Louis, Missouri 63103
                               (314) 621-3222

         1-2967                Union Electric Company                                               43-0559760
                               (Missouri Corporation)
                               1901 Chouteau Avenue
                               St. Louis, Missouri 63103
                               (314) 621-3222

         1-3672                Central Illinois Public Service Company                              37-0211380
                               (Illinois Corporation)
                               607 East Adams Street
                               Springfield, Illinois 62739
                               (217) 523-3600
<PAGE>

         333-56594             Ameren Energy Generating Company                                     37-1395586
                               (Illinois Corporation)
                               1901 Chouteau Avenue
                               St. Louis, Missouri 63103
                               (314) 621-3222

         2-95569               CILCORP Inc.                                                         37-1169387
                               (Illinois Corporation)
                               300 Liberty Street
                               Peoria, Illinois 61602
                               (309) 677-5230

         1-2732                Central Illinois Light Company                                       37-0211050
                               (Illinois Corporation)
                               300 Liberty Street
                               Peoria, Illinois 61602
                               (309) 677-5230
</TABLE>

<PAGE>


ITEM 5. OTHER EVENTS AND REGULATION FD DISCLOSURE.

     On December 5, 2003,  Ameren  Corporation (Ameren)  issued a press
release  announcing  that  it is  in  exclusive  discussions  with  Dynegy  Inc.
regarding the possible  acquisition  of Illinois  Power  Company.  A copy of the
press release is attached hereto as Exhibit 99.1 and is  incorporated  herein by
this reference.

     This combined Form 8-K is being filed separately by Ameren,  Union Electric
Company,  Central  Illinois  Public Service  Company,  Ameren Energy  Generating
Company,   CILCORP  Inc.  and  Central  Illinois  Light  Company  (Registrants).
Information  contained  herein  relating to any  individual  registrant has been
filed  by  such  registrant  on  its  own  behalf.   No  registrant   makes  any
representation as to information relating to any other registrant.


ITEM 7. FINANCIAL STATEMENTS AND EXHIBITS.

     (a) Financial Statements: Not applicable

     (b) Pro Forma Financial Information: Not applicable

     (c) Exhibits:


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

     99.1    Press Release issued on December 5, 2003 by Ameren Corporation.


<PAGE>

                                   SIGNATURES

     Pursuant to the  requirements of the Exchange Act, each registrant has duly
caused this report to be signed on its behalf by the undersigned  thereunto duly
authorized. The signature for each undersigned company shall be deemed to relate
only to matters having reference to such company or its subsidiaries.



                                       AMEREN CORPORATION
                                           (Registrant)

                                         /s/ Martin J. Lyons
                                 -------------------------------------
                                            Martin J. Lyons
                                      Vice President and Controller

                                      (Principal Accounting Officer)



                                     UNION ELECTRIC COMPANY
                                           (Registrant)

                                         /s/ Martin J. Lyons
                                 -------------------------------------
                                           Martin J. Lyons
                                      Vice President and Controller

                                      (Principal Accounting Officer)



                               CENTRAL ILLINOIS PUBLIC SERVICE COMPANY
                                           (Registrant)

                                         /s/ Martin J. Lyons
                                 -------------------------------------
                                           Martin J. Lyons
                                      Vice President and Controller

                                      (Principal Accounting Officer)



                                   AMEREN ENERGY GENERATING COMPANY
                                           (Registrant)

                                         /s/ Martin J. Lyons
                                 -------------------------------------
                                           Martin J. Lyons
                                      Vice President and Controller

                                      (Principal Accounting Officer)



<PAGE>


                                           CILCORP Inc.
                                           (Registrant)

                                         /s/ Martin J. Lyons
                                 -------------------------------------
                                           Martin J. Lyons
                                      Vice President and Controller

                                      (Principal Accounting Officer)




                                   Central Illinois Light Company
                                           (Registrant)

                                         /s/ Martin J. Lyons
                                 -------------------------------------
                                           Martin J. Lyons
                                      Vice President and Controller

                                      (Principal Accounting Officer)


Date:  December 5, 2003


<PAGE>


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

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

  99.1        Press release issued on December 5, 2003 by Ameren Corporation.
[{"type": "8-K", "sequence": "1", "filename": "aee8k120503.txt", "description": "AMEREN 8K 12052003", "secsgml_size_bytes": 7431}]
[{"company-data": {"conformed-name": "UNION ELECTRIC CO", "cik": "0000100826", "assigned-sic": "4911", "irs-number": "430559760", "state-of-incorporation": "MO", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "001-02967", "film-number": "031040630"}, "business-address": {"street1": "1901 CHOUTEAU AVENUE", "street2": "MC 1370", "city": "ST LOUIS", "state": "MO", "zip": "63166", "phone": "3146213222"}, "mail-address": {"street1": "1901 CHOUTEAU AVENUE", "street2": "MC 1370", "city": "ST LOUIS", "state": "MO", "zip": "63166"}}, {"company-data": {"conformed-name": "CENTRAL ILLINOIS LIGHT CO", "cik": "0000018651", "assigned-sic": "4931", "irs-number": "370211050", "state-of-incorporation": "IL", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "001-02732", "film-number": "031040632"}, "business-address": {"street1": "300 LIBERTY ST", "city": "PEORIA", "state": "IL", "zip": "61602", "phone": "3096758810"}, "mail-address": {"street1": "1901 CHOUTEAU AVE", "city": "ST. LOUIS", "state": "MO", "zip": "63103"}}, {"company-data": {"conformed-name": "CENTRAL ILLINOIS PUBLIC SERVICE CO", "cik": "0000018654", "assigned-sic": "4931", "irs-number": "370211380", "state-of-incorporation": "IL", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "001-03672", "film-number": "031040633"}, "business-address": {"street1": "607 E ADAMS ST", "city": "SPRINGFIELD", "state": "IL", "zip": "62739", "phone": "3145543356"}, "mail-address": {"street1": "CENTRAL ILLINOIS PUBLIC SERVICE CO", "street2": "607 E ADAMS ST", "city": "SPRINGFIELD", "state": "IL", "zip": "62739"}}, {"company-data": {"conformed-name": "CILCORP INC", "cik": "0000762129", "assigned-sic": "4931", "irs-number": "371169387", "state-of-incorporation": "IL", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "002-95569", "film-number": "031040631"}, "business-address": {"street1": "300 LIBERTY ST", "street2": "STE 300", "city": "PEORIA", "state": "IL", "zip": "61602", "phone": "3096758810"}, "mail-address": {"street1": "1901 CHOUTEAU AVE MC-1370", "city": "ST. LOUIS", "state": "MO", "zip": "63103"}}, {"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": "031040629"}, "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"}}, {"company-data": {"conformed-name": "AMERENENERGY GENERATING CO", "cik": "0001135361", "assigned-sic": "4911", "irs-number": "371395586", "state-of-incorporation": "IL", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "333-56594", "film-number": "031040634"}, "business-address": {"street1": "1901 CHOUTEAU AVENUE", "city": "ST LOUIS", "state": "MO", "zip": "63103", "phone": "3145543922"}, "mail-address": {"street1": "1901 CHOUTEAU AVENUE", "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):
                                December 5, 2003
Exact Name of Registrant as specified in its charter;
         Commission            State of Incorporation;                                         IRS Employer
         File Number           Address and Telephone Number                                    Identification No.
         -----------           ----------------------------                                    ------------------
1-14756               Ameren Corporation                                                   43-1723446
                               (Missouri Corporation)
                               1901 Chouteau Avenue
                               St. Louis, Missouri 63103
                               (314) 621-3222

         1-2967                Union Electric Company                                               43-0559760
                               (Missouri Corporation)
                               1901 Chouteau Avenue
                               St. Louis, Missouri 63103
                               (314) 621-3222

         1-3672                Central Illinois Public Service Company                              37-0211380
                               (Illinois Corporation)
                               607 East Adams Street
                               Springfield, Illinois 62739
                               (217) 523-3600
333-56594             Ameren Energy Generating Company                                     37-1395586
                               (Illinois Corporation)
                               1901 Chouteau Avenue
                               St. Louis, Missouri 63103
                               (314) 621-3222

         2-95569               CILCORP Inc.                                                         37-1169387
                               (Illinois Corporation)
                               300 Liberty Street
                               Peoria, Illinois 61602
                               (309) 677-5230

         1-2732                Central Illinois Light Company                                       37-0211050
                               (Illinois Corporation)
                               300 Liberty Street
                               Peoria, Illinois 61602
                               (309) 677-5230
ITEM 5. OTHER EVENTS AND REGULATION FD DISCLOSURE.

     On December 5, 2003,  Ameren  Corporation (Ameren)  issued a press
release  announcing  that  it is  in  exclusive  discussions  with  Dynegy  Inc.
regarding the possible  acquisition  of Illinois  Power  Company.  A copy of the
press release is attached hereto as Exhibit 99.1 and is  incorporated  herein by
this reference.

     This combined Form 8-K is being filed separately by Ameren,  Union Electric
Company,  Central  Illinois  Public Service  Company,  Ameren Energy  Generating
Company,   CILCORP  Inc.  and  Central  Illinois  Light  Company  (Registrants).
Information  contained  herein  relating to any  individual  registrant has been
filed  by  such  registrant  on  its  own  behalf.   No  registrant   makes  any
representation as to information relating to any other registrant.

ITEM 7. FINANCIAL STATEMENTS AND EXHIBITS.

     (a) Financial Statements: Not applicable

     (b) Pro Forma Financial Information: Not applicable

     (c) Exhibits:

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

     99.1    Press Release issued on December 5, 2003 by Ameren Corporation.
SIGNATURES

     Pursuant to the  requirements of the Exchange Act, each registrant has duly
caused this report to be signed on its behalf by the undersigned  thereunto duly
authorized. The signature for each undersigned company shall be deemed to relate
only to matters having reference to such company or its subsidiaries.

                                       AMEREN CORPORATION
                                           (Registrant)

                                         /s/ Martin J. Lyons
                                 -------------------------------------
                                            Martin J. Lyons
                                      Vice President and Controller

                                      (Principal Accounting Officer)

                                     UNION ELECTRIC COMPANY
                                           (Registrant)

                                         /s/ Martin J. Lyons
                                 -------------------------------------
                                           Martin J. Lyons
                                      Vice President and Controller

                                      (Principal Accounting Officer)

                               CENTRAL ILLINOIS PUBLIC SERVICE COMPANY
                                           (Registrant)

                                         /s/ Martin J. Lyons
                                 -------------------------------------
                                           Martin J. Lyons
                                      Vice President and Controller

                                      (Principal Accounting Officer)

                                   AMEREN ENERGY GENERATING COMPANY
                                           (Registrant)

                                         /s/ Martin J. Lyons
                                 -------------------------------------
                                           Martin J. Lyons
                                      Vice President and Controller

                                      (Principal Accounting Officer)
CILCORP Inc.
                                           (Registrant)

                                         /s/ Martin J. Lyons
                                 -------------------------------------
                                           Martin J. Lyons
                                      Vice President and Controller

                                      (Principal Accounting Officer)

                                   Central Illinois Light Company
                                           (Registrant)

                                         /s/ Martin J. Lyons
                                 -------------------------------------
                                           Martin J. Lyons
                                      Vice President and Controller

                                      (Principal Accounting Officer)

Date:  December 5, 2003
Exhibit Index
                                  -------------

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

  99.1        Press release issued on December 5, 2003 by Ameren Corporation.