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 10, 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

</TABLE>

<PAGE>


ITEM 5. OTHER EVENTS AND REGULATION FD DISCLOSURE.

     Reference is made to Note 3 - Rate and Regulatory Matters (Missouri Gas) in
the "Combined Notes to Financial Statements (Unaudited)" in Ameren Corporation's
and Union Electric Company's (AmerenUE) Form 10-Q for the quarterly period ended
September  30,  2003 for a  discussion  of  AmerenUE's  May 2003  request to the
Missouri  Public  Service  Commission  for an increase  in natural gas  delivery
rates.  On  December  10,  2003,  Ameren  Corporation  issued  a  press  release
announcing  that AmerenUE has entered into a settlement with the Missouri Public
Service  Commission  staff,  the  Office  of  Public  Counsel  and the  Missouri
Department  of Natural  Resources  to implement  increased  natural gas delivery
rates.  The settlement is subject to review and approval by the Missouri  Public
Service  Commission.  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  Corporation and
Union Electric 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 10, 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)





Date:  December 10, 2003



<PAGE>




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

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

      99.1      Press release issued on December 10, 2003 by Ameren Corporation.
[{"type": "8-K", "sequence": "1", "filename": "aee_ue8k12102003.txt", "description": "AMEREN/UE 8K 12102003", "secsgml_size_bytes": 4697}]
[{"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": "031047803"}, "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": "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": "031047802"}, "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):
                                December 10, 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
ITEM 5. OTHER EVENTS AND REGULATION FD DISCLOSURE.

     Reference is made to Note 3 - Rate and Regulatory Matters (Missouri Gas) in
the "Combined Notes to Financial Statements (Unaudited)" in Ameren Corporation's
and Union Electric Company's (AmerenUE) Form 10-Q for the quarterly period ended
September  30,  2003 for a  discussion  of  AmerenUE's  May 2003  request to the
Missouri  Public  Service  Commission  for an increase  in natural gas  delivery
rates.  On  December  10,  2003,  Ameren  Corporation  issued  a  press  release
announcing  that AmerenUE has entered into a settlement with the Missouri Public
Service  Commission  staff,  the  Office  of  Public  Counsel  and the  Missouri
Department  of Natural  Resources  to implement  increased  natural gas delivery
rates.  The settlement is subject to review and approval by the Missouri  Public
Service  Commission.  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  Corporation and
Union Electric 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 10, 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)

Date:  December 10, 2003
Exhibit Index
                                  -------------

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

      99.1      Press release issued on December 10, 2003 by Ameren Corporation.