<PAGE>   1
         AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JANUARY 5, 1998
                                       REGISTRATION STATEMENT NO. 33-___________
================================================================================

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                                    FORM S-8
                             REGISTRATION STATEMENT
                                    UNDER THE
                             SECURITIES ACT OF 1933

         --------------------------------------------------------------



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

<TABLE>
<S><C>
      STATE OF MISSOURI                                                              43-1723446
  (State or other jurisdiction                                                     (IRS Employer
of incorporation or organization)                                                Identification No.)
</TABLE>
                              1901 CHOUTEAU AVENUE
                            ST. LOUIS, MISSOURI 63103
          (Address, including zip code, of principal executive offices)

         --------------------------------------------------------------


     CENTRAL ILLINOIS PUBLIC SERVICE COMPANY EMPLOYEE LONG-TERM SAVINGS PLAN
CENTRAL ILLINOIS PUBLIC SERVICE COMPANY EMPLOYEE LONG-TERM SAVINGS PLAN - IUOE
LOCAL NO.148 CENTRAL ILLINOIS PUBLIC SERVICE COMPANY EMPLOYEE LONG-TERM SAVINGS
PLAN - IBEW LOCAL NO. 702 
                           (Full titles of the plans)

                DONALD E. BRANDT, Senior Vice President, Finance
                          JAMES C. THOMPSON, Secretary
                 1901 Chouteau Avenue, St. Louis, Missouri 63103
                                 (314) 621-3222
                    (Names, address and telephone number,
                 including area code, of agents for service)

                         CALCULATION OF REGISTRATION FEE
<TABLE>
<CAPTION>
=================================================================================================================================
                                                                     PROPOSED
           TITLE OF SECURITIES                   AMOUNT               MAXIMUM          PROPOSED MAXIMUM          AMOUNT OF
            TO BE REGISTERED                      TO BE           OFFERING PRICE           AGGREGATE           REGISTRATION
                                               REGISTERED            PER UNIT*          OFFERING PRICE              FEE
---------------------------------------------------------------------------------------------------------------------------------
<S>                                          <C>                     <C>                     <C>                     <C>   
COMMON STOCK, $.01 PAR VALUE,
INCLUDING RELATED PLAN INTERESTS -
EMPLOYEE LONG-TERM SAVINGS PLAN              200,000 SHARES          $42.2816                $8,456,320              $2,563
---------------------------------------------------------------------------------------------------------------------------------
COMMON STOCK, $.01 PAR VALUE,
INCLUDING RELATED PLAN INTERESTS -
EMPLOYEE LONG-TERM SAVINGS PLAN              200,000 SHARES          $42.2816                $8,456,320              $2,563
IUOE LOCAL NO. 148
---------------------------------------------------------------------------------------------------------------------------------
COMMON STOCK, $.01 PAR VALUE,
INCLUDING RELATED PLAN INTERESTS -
EMPLOYEE LONG-TERM SAVINGS PLAN              200,000 SHARES          $42.2816                $8,456,320              $2,563
IBEW LOCAL NO. 702
---------------------------------------------------------------------------------------------------------------------------------
                                             600,000 SHARES          $42.2816               $25,368,960              $7,689
         TOTAL
=================================================================================================================================
</TABLE>


*   Calculated in accordance with Rule 457(h) on the basis of the average of the
    high and low prices of Union Electric Company Common Stock as reported on
    the New York Stock Exchange Composite Tape on December 26, 1997.

================================================================================

<PAGE>   2



                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE

         The following documents, previously filed with the Commission by CIPSCO
Incorporated ("CIPSCO") (File No. 1-10628), Union Electric Company ("Union
Electric") (File No. 1-2967), the Registrant, the Central Illinois Public
Service Company Employee Long-Term Savings Plan, the Central Illinois Public
Service Company Employee Long-Term Savings Plan - IUOE Local No. 148 and the
Central Illinois Public Service Company Employee Long-Term Savings Plan - IBEW
Local No. 702 (such Plans being referred to herein, collectively, as the
"Plans") pursuant to the Securities Exchange Act of 1934, as amended, are
incorporated by reference in this Registration Statement:

         1. CIPSCO'S Annual Report on Form 10-K for the year ended December 31,
1996.

         2. CIPSCO's Quarterly Reports on Form 10-Q for the quarters ended March
31, 1997, June 30, 1997 and September 30, 1997.

         3. CIPSCO's Current Reports on Form 8-K dated March 20, November 24,
December 16 and December 31, 1997.

         4. Union Electric's Annual Report on Form 10-K for the year ended
December 31, 1996.

         5. Union Electric's Quarterly Reports on Form 10-Q for the quarters
ended March 31, 1997, June 30, 1997 and September 30, 1997.

         6. Union Electric's Current Reports on Form 8-K dated December 16 and
December 31, 1997.

         7. The Registrant's Current Report on Form 8-K dated December 31, 1997.

         8. The Registrant's Registration Statement on Form S-4 (Reg. No.
33-64165), filed November 13, 1995, which includes a description of the Common
Stock of the Registrant.

         9. The Annual Report on Form 11-K for the year ended December 31, 1996
of the Central Illinois Public Service Company Master Long-Term Savings Trust,
relating to the Central Illinois Public Service Company Employee Long-Term
Savings Plan, the Central Illinois Public Service Company Employee Long-Term
Savings Plan - IUOE Local No. 148 and the Central Illinois Public Service
Company Employee Long-Term Savings Plan - IBEW Local No. 702.

All documents subsequently filed by the Registrant or the Plans pursuant to
Sections 13(a), 13(c), 14 and 15(d) of the Securities Exchange Act of 1934, as
amended, prior to the filing of a post-effective amendment which indicates that
all securities offered have been sold or which deregisters all securities then
remaining unsold, shall be deemed to be incorporated by reference herein and to
be a part hereof from the date of the filing of such documents.

ITEM 4.  DESCRIPTION OF SECURITIES

         Not Applicable.


                                     II - 1

<PAGE>   3
ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL

         William E, Jaudes, Esq., Vice President and General Counsel of the
Registrant, will pass upon the legality of the shares of Common Stock of the
Registrant and Plan interests to be issued under the Plans.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

         Article IV of the Registrant's By-Laws, consistent with the applicable
provisions of the Missouri General and Business Corporation Law (the "MGBCL"),
provides for indemnification of directors and officers. These provisions provide
that any person shall be indemnified for expenses and liabilities imposed upon
such person in connection with any threatened, pending or completed action,
suit, or proceeding, whether civil, criminal, administrative or investigative,
other than an action by or in the right of the Registrant, by reason of the fact
that such person is or was a director, officer, employee or agent of the
Registrant, or is or was serving at the request of the Registrant as a director,
officer, employee or agent of another corporation, partnership, joint venture,
trust or other enterprise, against expenses, including attorneys' fees,
judgments, fines and amounts paid in settlement actually and reasonably incurred
by such person in connection with such action, suit or proceeding if such person
acted in good faith and in a manner such person reasonably believed to be in or
not opposed to the best interests of the Registrant, and, with respect to any
criminal action or proceeding, had no reasonable cause to believe his conduct
was unlawful.

         In a proceeding brought by or in the right of the Registrant, no
indemnification shall be made with respect to any claim as to which an officer
or director has been adjudged to have been liable to Registrant, unless the
court determines that such a person is reasonably and fairly entitled to
indemnification for expenses. However, no indemnification shall be made in
respect of any claim, issue or matter as to which such person shall have been
adjudged to be liable for negligence or misconduct in the performance of his
duty to the Registrant unless and only to the extent that the court in which the
action or suit was brought determines upon application that, despite the
adjudication of liability and in view of all the circumstances of the case, the
person is fairly and reasonably entitled to indemnity for such expenses which
the court shall deem proper.

         The By-laws, consistent with the applicable provisions of the MGBCL,
provide that indemnification shall be made by the Registrant only if a
determination has been made by a majority vote of a quorum of the disinterested
directors or by the shareholders or by independent legal counsel, that the
director or officer met the required standard of conduct. The Registrant is
authorized to purchase liability insurance on behalf of an officer or director
whether or not the Registrant would otherwise have the power to indemnify such
person.

         The By-laws, consistent with the applicable provisions of the MGBCL,
further provide that, in addition to the indemnities described in the preceding
paragraphs, the Registrant will further indemnity its officers and directors to
the maximum extent permitted by law, provided that no indemnity may be given for
conduct that is adjudged to be knowingly fraudulent, deliberately dishonest, or
willful misconduct.

ITEM 7.  EXEMPTIONS FROM REGISTRATION CLAIMED

         Not Applicable.

ITEM 8.  EXHIBITS

         Exhibit No.

           4.1        Article III of the Restated Certificate of Incorporation
                      of the Registrant (incorporated by reference to Exhibit
                      3(i) of the Form S-4 Registration Statement of the
                      Registrant, Reg.
                      No. 33-64165).


                                     II - 2

<PAGE>   4
           4.2        By-Laws of the Registrant (incorporated by reference to
                      Annex G of the Joint Proxy Statement/Prospectus included
                      in the Form S-4 Registration Statement of the Registrant,
                      Reg. No. 33-64165).

           5          Opinion of William E. Jaudes as to the legality of the
                      securities being issued.

          23.1        Consent of Price Waterhouse LLP.

          23.2        Consent of Arthur Andersen LLP.

          23.3        Consent of William E. Jaudes (included in Exhibit 5).

          24          Powers of Attorney.

ITEM 9.  UNDERTAKINGS

  (a)     The undersigned Registrant hereby undertakes:

          (1) To file, during any period in which offers or sales are being
made, a post-effective amendment to this registration statement:

                  (i) To include any prospectus required by Section 10(a)(3) of
the Securities Act of 1933;

                  (ii) To reflect in the prospectus any facts or events arising
after the effective date of the registration statement (or the most recent
post-effective amendment thereof) which, individually or in the aggregate,
represent a fundamental change in the information set forth in the registration
statement. Notwithstanding the foregoing, any increase or decrease in volume of
securities offered (if the total dollar value of securities offered would not
exceed that which was registered) and any deviation from the low or high end of
the estimated maximum offering range may be reflected in the form of prospectus
filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the
changes in volume and price represent no more than a 20% change in the maximum
aggregate offering price set forth in the "Calculation of Registration Fee"
table in the effective registration statement;

                  (iii) To include any material information with respect to the
plan of distribution not previously disclosed in the registration statement or
any material change to such information in the registration statement;

Provided, however, that paragraphs (a)(l)(i) and (a)(l)(ii) do not apply in the
registration statement is on Form S-3, Form S-8 or Form F-3, and the information
required to be included in a post-effective amendment by those paragraphs is
contained in periodic reports filed with or furnished to the Commission by the
registrant pursuant to Section 13 or Section 15(d) of the Securities Exchange
Act of 1934 that are incorporated by reference in this registration statement.

          (2) That, for the purpose of determining any liability under the
Securities Act of 1933, each such post-effective amendment shall be deemed to be
a new registration statement relating to the securities offered therein and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

          (3) To remove from registration by means of a post-effective amendment
any of the securities being registered which remain unsold at the termination of
the offering.


                                     II - 3

<PAGE>   5
  (b) The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act of 1933, each filing of the
registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Securities Exchange act of 1934 (and, where applicable, each filing of an
employee benefit plan's annual report pursuant to Section 15(d) of the
Securities Exchange Act of 1934) that is incorporated by reference in the
registration statement shall be deemed to be a new registration statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.

  (c) Insofar as indemnification for liabilities arising under the Securities
Act of 1933 may be permitted to directors, officers and controlling persons of
the Registrant pursuant to the provisions referred to in Item 6 of this
Registration Statement, or otherwise, the Registrant has been advised that in
the opinion of the Securities and Exchange Commission such indemnification is
against public policy as expressed in the Act and is, therefore, unenforceable.
In the event that a claim for indemnification against such liabilities (other
than the payment by the Registrant of expenses incurred or paid by a director,
officer or controlling person of the Registrant in the successful defense of any
action, suit or proceeding) is asserted by such director, officer or controlling
person in connection with the securities being registered, the Registrant will,
unless in the opinion of its counsel the matter has been settled by controlling
precedent, submit to a court of appropriate jurisdiction the question whether
such indemnification by it is against public policy as expressed in the Act and
will be governed by the final adjudication of such issue.


                                     II - 4

<PAGE>   6
                                   SIGNATURES


          THE REGISTRANT. Pursuant to the requirements of the Securities Act of
1933, the Registrant certifies that it has reasonable grounds to believe that it
meets all of the requirements for filing on Form S-8 and has duly caused this
Registration Statement to be signed on its behalf by the undersigned thereunto
duly authorized, in the City of St. Louis, State of Missouri, on the 2nd day of
January, 1998.


                                      AMEREN CORPORATION



                                      By        /s/Donald E. Brandt
                                         ---------------------------------------
                                                 DONALD E. BRANDT
                                          Senior Vice President, Finance


         Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the date above indicated.


            SIGNATURE                                   TITLE



/s/   Charles W. Mueller*                  Chairman, President and Chief
   -------------------------------        Executive Officer and Director
      CHARLES W. MUELLER                   (Principal Executive Officer)

/s/   Donald E. Brandt
   -------------------------------
      DONALD E. BRANDT                      Senior Vice President, Finance
                                   (Principal Financial and Accounting Officer)


/s/  Clifford L. Greenwalt*
   -------------------------------
     CLIFFORD L. GREENWALT                          Director


/s/   William E. Cornelius*
   -------------------------------
      WILLIAM E. CORNELIUS                          Director


/s/    Thomas A. Hays*
   -------------------------------
       THOMAS A. HAYS                               Director


/s/    Richard A. Liddy*
   -------------------------------
       RICHARD A. LIDDY                             Director


/s/    

   -------------------------------
       GORDAN R. LOHMAN                             Director

                                     II - 5

<PAGE>   7
/s/  Richard A. Lumpkin*
   -------------------------------
     RICHARD A. LUMPKIN                             Director


/s/   John Peters MacCarthy*
   -------------------------------
      JOHN PETERS MACCARTHY                         Director

/s/
   -------------------------------
       HANNE M. MERRIMAN                            Director


/s/  Paul L. Miller, Jr.*
   -------------------------------
      PAUL L. MILLER, JR.                           Director


/s/    Robert H. Quenon*
   -------------------------------
       ROBERT H. QUENON                             Director


/s/    Harvey Saligman*
   -------------------------------
        HARVEY SALIGMAN                             Director


/s/   Charles J. Schukai*
   -------------------------------
      CHARLES J. SCHUKAI                            Director


/s/  Janet McAfee Weakley*
   -------------------------------
     JANET MCAFEE WEAKLEY                           Director


/s/
   -------------------------------
       JAMES W. WOGSLAND                            Director




                                        *By     /s/James C. Thompson
                                            -------------------------------
                                                 JAMES C. THOMPSON
                                                 Attorney-In-Fact

                                     II - 6

<PAGE>   8
       The Plans. Pursuant to the requirements of the Securities Act of 1933,
the persons who administer the undersigned employee benefit plans have duly
caused this Registration Statement to be signed on their behalf by the
undersigned thereunto duly authorized, in the City of St. Louis, State of
Missouri, on the 2nd day of January, 1998.


                         CENTRAL ILLINOIS PUBLIC SERVICE COMPANY
                         EMPLOYEE LONG-TERM SAVINGS PLAN

                         CENTRAL ILLINOIS PUBLIC SERVICE COMPANY EMPLOYEE
                         LONG-TERM SAVINGS PLAN - IUOE LOCAL NO. 148

                         CENTRAL ILLINOIS PUBLIC SERVICE COMPANY EMPLOYEE
                         LONG-TERM SAVINGS PLAN - IBEW LOCAL NO. 702



                         By         /s/Donald E. Brandt 
                            -----------------------------------------------
                                     DONALD E. BRANDT 
                               Senior Vice President, Finance 
                                     Ameren Corporation


                                     II - 7

<PAGE>   9

                                  EXHIBIT INDEX



Exhibit No.

   4.1       Article III of the Restated Certificate of Incorporation of the
             Registrant (incorporated by reference to Exhibit 3(i) of the Form
             S-4 Registration Statement of the Registrant, Reg. No. 33-64165).

   4.2       By-Laws of the Registrant (incorporated by reference to Annex G of
             the Joint Proxy Statement/Prospectus included in the Form S-4
             Registration Statement of the Registrant, Reg. No. 33-64165).

   5         Opinion of William E. Jaudes as to the legality of the securities
             being issued.

  23.1       Consent of Price Waterhouse LLP.

  23.2       Consent of Arthur Andersen LLP.

  23.3       Consent of William E. Jaudes (included in Exhibit 5).

  24         Powers of Attorney.



              All Exhibits are filed electronically with Form S-8.


                                     II - 8
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 21927}]
{"company-data": {"conformed-name": "AMEREN CORP", "cik": "0001002910", "assigned-sic": "1000", "irs-number": "431723446", "state-of-incorporation": "MO", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-43743", "film-number": "98501107"}, "business-address": {"street1": "1901 CHOUTEAU AVE", "city": "ST LOUIS", "state": "MO", "zip": "63103", "phone": "3146213222"}, "mail-address": {"street1": "1901 CHOUTEAU AVE", "city": "ST LOUIS", "state": "MO", "zip": "63103"}}
1
         AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JANUARY 5, 1998
                                       REGISTRATION STATEMENT NO. 33-___________
================================================================================

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                                    FORM S-8
                             REGISTRATION STATEMENT
                                    UNDER THE
                             SECURITIES ACT OF 1933

         --------------------------------------------------------------

                               AMEREN CORPORATION
             (Exact name of registrant as specified in its charter)
STATE OF MISSOURI                                                              43-1723446
  (State or other jurisdiction                                                     (IRS Employer
of incorporation or organization)                                                Identification No.)
1901 CHOUTEAU AVENUE
                            ST. LOUIS, MISSOURI 63103
          (Address, including zip code, of principal executive offices)

         --------------------------------------------------------------

     CENTRAL ILLINOIS PUBLIC SERVICE COMPANY EMPLOYEE LONG-TERM SAVINGS PLAN
CENTRAL ILLINOIS PUBLIC SERVICE COMPANY EMPLOYEE LONG-TERM SAVINGS PLAN - IUOE
LOCAL NO.148 CENTRAL ILLINOIS PUBLIC SERVICE COMPANY EMPLOYEE LONG-TERM SAVINGS
PLAN - IBEW LOCAL NO. 702 
                           (Full titles of the plans)

                DONALD E. BRANDT, Senior Vice President, Finance
                          JAMES C. THOMPSON, Secretary
                 1901 Chouteau Avenue, St. Louis, Missouri 63103
                                 (314) 621-3222
                    (Names, address and telephone number,
                 including area code, of agents for service)

                         CALCULATION OF REGISTRATION FEE
=================================================================================================================================
                                                                     PROPOSED
           TITLE OF SECURITIES                   AMOUNT               MAXIMUM          PROPOSED MAXIMUM          AMOUNT OF
            TO BE REGISTERED                      TO BE           OFFERING PRICE           AGGREGATE           REGISTRATION
                                               REGISTERED            PER UNIT*          OFFERING PRICE              FEE
---------------------------------------------------------------------------------------------------------------------------------
COMMON STOCK, $.01 PAR VALUE,
INCLUDING RELATED PLAN INTERESTS -
EMPLOYEE LONG-TERM SAVINGS PLAN              200,000 SHARES          $42.2816                $8,456,320              $2,563
---------------------------------------------------------------------------------------------------------------------------------
COMMON STOCK, $.01 PAR VALUE,
INCLUDING RELATED PLAN INTERESTS -
EMPLOYEE LONG-TERM SAVINGS PLAN              200,000 SHARES          $42.2816                $8,456,320              $2,563
IUOE LOCAL NO. 148
---------------------------------------------------------------------------------------------------------------------------------
COMMON STOCK, $.01 PAR VALUE,
INCLUDING RELATED PLAN INTERESTS -
EMPLOYEE LONG-TERM SAVINGS PLAN              200,000 SHARES          $42.2816                $8,456,320              $2,563
IBEW LOCAL NO. 702
---------------------------------------------------------------------------------------------------------------------------------
                                             600,000 SHARES          $42.2816               $25,368,960              $7,689
         TOTAL
=================================================================================================================================
*   Calculated in accordance with Rule 457(h) on the basis of the average of the
    high and low prices of Union Electric Company Common Stock as reported on
    the New York Stock Exchange Composite Tape on December 26, 1997.

================================================================================
2

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE

         The following documents, previously filed with the Commission by CIPSCO
Incorporated ("CIPSCO") (File No. 1-10628), Union Electric Company ("Union
Electric") (File No. 1-2967), the Registrant, the Central Illinois Public
Service Company Employee Long-Term Savings Plan, the Central Illinois Public
Service Company Employee Long-Term Savings Plan - IUOE Local No. 148 and the
Central Illinois Public Service Company Employee Long-Term Savings Plan - IBEW
Local No. 702 (such Plans being referred to herein, collectively, as the
"Plans") pursuant to the Securities Exchange Act of 1934, as amended, are
incorporated by reference in this Registration Statement:

         1. CIPSCO'S Annual Report on Form 10-K for the year ended December 31,
1996.

         2. CIPSCO's Quarterly Reports on Form 10-Q for the quarters ended March
31, 1997, June 30, 1997 and September 30, 1997.

         3. CIPSCO's Current Reports on Form 8-K dated March 20, November 24,
December 16 and December 31, 1997.

         4. Union Electric's Annual Report on Form 10-K for the year ended
December 31, 1996.

         5. Union Electric's Quarterly Reports on Form 10-Q for the quarters
ended March 31, 1997, June 30, 1997 and September 30, 1997.

         6. Union Electric's Current Reports on Form 8-K dated December 16 and
December 31, 1997.

         7. The Registrant's Current Report on Form 8-K dated December 31, 1997.

         8. The Registrant's Registration Statement on Form S-4 (Reg. No.
33-64165), filed November 13, 1995, which includes a description of the Common
Stock of the Registrant.

         9. The Annual Report on Form 11-K for the year ended December 31, 1996
of the Central Illinois Public Service Company Master Long-Term Savings Trust,
relating to the Central Illinois Public Service Company Employee Long-Term
Savings Plan, the Central Illinois Public Service Company Employee Long-Term
Savings Plan - IUOE Local No. 148 and the Central Illinois Public Service
Company Employee Long-Term Savings Plan - IBEW Local No. 702.

All documents subsequently filed by the Registrant or the Plans pursuant to
Sections 13(a), 13(c), 14 and 15(d) of the Securities Exchange Act of 1934, as
amended, prior to the filing of a post-effective amendment which indicates that
all securities offered have been sold or which deregisters all securities then
remaining unsold, shall be deemed to be incorporated by reference herein and to
be a part hereof from the date of the filing of such documents.

ITEM 4.  DESCRIPTION OF SECURITIES

         Not Applicable.

                                     II - 1
3
ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL

         William E, Jaudes, Esq., Vice President and General Counsel of the
Registrant, will pass upon the legality of the shares of Common Stock of the
Registrant and Plan interests to be issued under the Plans.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

         Article IV of the Registrant's By-Laws, consistent with the applicable
provisions of the Missouri General and Business Corporation Law (the "MGBCL"),
provides for indemnification of directors and officers. These provisions provide
that any person shall be indemnified for expenses and liabilities imposed upon
such person in connection with any threatened, pending or completed action,
suit, or proceeding, whether civil, criminal, administrative or investigative,
other than an action by or in the right of the Registrant, by reason of the fact
that such person is or was a director, officer, employee or agent of the
Registrant, or is or was serving at the request of the Registrant as a director,
officer, employee or agent of another corporation, partnership, joint venture,
trust or other enterprise, against expenses, including attorneys' fees,
judgments, fines and amounts paid in settlement actually and reasonably incurred
by such person in connection with such action, suit or proceeding if such person
acted in good faith and in a manner such person reasonably believed to be in or
not opposed to the best interests of the Registrant, and, with respect to any
criminal action or proceeding, had no reasonable cause to believe his conduct
was unlawful.

         In a proceeding brought by or in the right of the Registrant, no
indemnification shall be made with respect to any claim as to which an officer
or director has been adjudged to have been liable to Registrant, unless the
court determines that such a person is reasonably and fairly entitled to
indemnification for expenses. However, no indemnification shall be made in
respect of any claim, issue or matter as to which such person shall have been
adjudged to be liable for negligence or misconduct in the performance of his
duty to the Registrant unless and only to the extent that the court in which the
action or suit was brought determines upon application that, despite the
adjudication of liability and in view of all the circumstances of the case, the
person is fairly and reasonably entitled to indemnity for such expenses which
the court shall deem proper.

         The By-laws, consistent with the applicable provisions of the MGBCL,
provide that indemnification shall be made by the Registrant only if a
determination has been made by a majority vote of a quorum of the disinterested
directors or by the shareholders or by independent legal counsel, that the
director or officer met the required standard of conduct. The Registrant is
authorized to purchase liability insurance on behalf of an officer or director
whether or not the Registrant would otherwise have the power to indemnify such
person.

         The By-laws, consistent with the applicable provisions of the MGBCL,
further provide that, in addition to the indemnities described in the preceding
paragraphs, the Registrant will further indemnity its officers and directors to
the maximum extent permitted by law, provided that no indemnity may be given for
conduct that is adjudged to be knowingly fraudulent, deliberately dishonest, or
willful misconduct.

ITEM 7.  EXEMPTIONS FROM REGISTRATION CLAIMED

         Not Applicable.

ITEM 8.  EXHIBITS

         Exhibit No.

           4.1        Article III of the Restated Certificate of Incorporation
                      of the Registrant (incorporated by reference to Exhibit
                      3(i) of the Form S-4 Registration Statement of the
                      Registrant, Reg.
                      No. 33-64165).

                                     II - 2
4
           4.2        By-Laws of the Registrant (incorporated by reference to
                      Annex G of the Joint Proxy Statement/Prospectus included
                      in the Form S-4 Registration Statement of the Registrant,
                      Reg. No. 33-64165).

           5          Opinion of William E. Jaudes as to the legality of the
                      securities being issued.

          23.1        Consent of Price Waterhouse LLP.

          23.2        Consent of Arthur Andersen LLP.

          23.3        Consent of William E. Jaudes (included in Exhibit 5).

          24          Powers of Attorney.

ITEM 9.  UNDERTAKINGS

  (a)     The undersigned Registrant hereby undertakes:

          (1) To file, during any period in which offers or sales are being
made, a post-effective amendment to this registration statement:

                  (i) To include any prospectus required by Section 10(a)(3) of
the Securities Act of 1933;

                  (ii) To reflect in the prospectus any facts or events arising
after the effective date of the registration statement (or the most recent
post-effective amendment thereof) which, individually or in the aggregate,
represent a fundamental change in the information set forth in the registration
statement. Notwithstanding the foregoing, any increase or decrease in volume of
securities offered (if the total dollar value of securities offered would not
exceed that which was registered) and any deviation from the low or high end of
the estimated maximum offering range may be reflected in the form of prospectus
filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the
changes in volume and price represent no more than a 20% change in the maximum
aggregate offering price set forth in the "Calculation of Registration Fee"
table in the effective registration statement;

                  (iii) To include any material information with respect to the
plan of distribution not previously disclosed in the registration statement or
any material change to such information in the registration statement;

Provided, however, that paragraphs (a)(l)(i) and (a)(l)(ii) do not apply in the
registration statement is on Form S-3, Form S-8 or Form F-3, and the information
required to be included in a post-effective amendment by those paragraphs is
contained in periodic reports filed with or furnished to the Commission by the
registrant pursuant to Section 13 or Section 15(d) of the Securities Exchange
Act of 1934 that are incorporated by reference in this registration statement.

          (2) That, for the purpose of determining any liability under the
Securities Act of 1933, each such post-effective amendment shall be deemed to be
a new registration statement relating to the securities offered therein and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

          (3) To remove from registration by means of a post-effective amendment
any of the securities being registered which remain unsold at the termination of
the offering.

                                     II - 3
5
  (b) The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act of 1933, each filing of the
registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Securities Exchange act of 1934 (and, where applicable, each filing of an
employee benefit plan's annual report pursuant to Section 15(d) of the
Securities Exchange Act of 1934) that is incorporated by reference in the
registration statement shall be deemed to be a new registration statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.

  (c) Insofar as indemnification for liabilities arising under the Securities
Act of 1933 may be permitted to directors, officers and controlling persons of
the Registrant pursuant to the provisions referred to in Item 6 of this
Registration Statement, or otherwise, the Registrant has been advised that in
the opinion of the Securities and Exchange Commission such indemnification is
against public policy as expressed in the Act and is, therefore, unenforceable.
In the event that a claim for indemnification against such liabilities (other
than the payment by the Registrant of expenses incurred or paid by a director,
officer or controlling person of the Registrant in the successful defense of any
action, suit or proceeding) is asserted by such director, officer or controlling
person in connection with the securities being registered, the Registrant will,
unless in the opinion of its counsel the matter has been settled by controlling
precedent, submit to a court of appropriate jurisdiction the question whether
such indemnification by it is against public policy as expressed in the Act and
will be governed by the final adjudication of such issue.

                                     II - 4
6
                                   SIGNATURES

          THE REGISTRANT. Pursuant to the requirements of the Securities Act of
1933, the Registrant certifies that it has reasonable grounds to believe that it
meets all of the requirements for filing on Form S-8 and has duly caused this
Registration Statement to be signed on its behalf by the undersigned thereunto
duly authorized, in the City of St. Louis, State of Missouri, on the 2nd day of
January, 1998.

                                      AMEREN CORPORATION

                                      By        /s/Donald E. Brandt
                                         ---------------------------------------
                                                 DONALD E. BRANDT
                                          Senior Vice President, Finance

         Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the date above indicated.

            SIGNATURE                                   TITLE

/s/   Charles W. Mueller*                  Chairman, President and Chief
   -------------------------------        Executive Officer and Director
      CHARLES W. MUELLER                   (Principal Executive Officer)

/s/   Donald E. Brandt
   -------------------------------
      DONALD E. BRANDT                      Senior Vice President, Finance
                                   (Principal Financial and Accounting Officer)

/s/  Clifford L. Greenwalt*
   -------------------------------
     CLIFFORD L. GREENWALT                          Director

/s/   William E. Cornelius*
   -------------------------------
      WILLIAM E. CORNELIUS                          Director

/s/    Thomas A. Hays*
   -------------------------------
       THOMAS A. HAYS                               Director

/s/    Richard A. Liddy*
   -------------------------------
       RICHARD A. LIDDY                             Director

/s/    

   -------------------------------
       GORDAN R. LOHMAN                             Director

                                     II - 5
7
/s/  Richard A. Lumpkin*
   -------------------------------
     RICHARD A. LUMPKIN                             Director

/s/   John Peters MacCarthy*
   -------------------------------
      JOHN PETERS MACCARTHY                         Director

/s/
   -------------------------------
       HANNE M. MERRIMAN                            Director

/s/  Paul L. Miller, Jr.*
   -------------------------------
      PAUL L. MILLER, JR.                           Director

/s/    Robert H. Quenon*
   -------------------------------
       ROBERT H. QUENON                             Director

/s/    Harvey Saligman*
   -------------------------------
        HARVEY SALIGMAN                             Director

/s/   Charles J. Schukai*
   -------------------------------
      CHARLES J. SCHUKAI                            Director

/s/  Janet McAfee Weakley*
   -------------------------------
     JANET MCAFEE WEAKLEY                           Director

/s/
   -------------------------------
       JAMES W. WOGSLAND                            Director

                                        *By     /s/James C. Thompson
                                            -------------------------------
                                                 JAMES C. THOMPSON
                                                 Attorney-In-Fact

                                     II - 6
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       The Plans. Pursuant to the requirements of the Securities Act of 1933,
the persons who administer the undersigned employee benefit plans have duly
caused this Registration Statement to be signed on their behalf by the
undersigned thereunto duly authorized, in the City of St. Louis, State of
Missouri, on the 2nd day of January, 1998.

                         CENTRAL ILLINOIS PUBLIC SERVICE COMPANY
                         EMPLOYEE LONG-TERM SAVINGS PLAN

                         CENTRAL ILLINOIS PUBLIC SERVICE COMPANY EMPLOYEE
                         LONG-TERM SAVINGS PLAN - IUOE LOCAL NO. 148

                         CENTRAL ILLINOIS PUBLIC SERVICE COMPANY EMPLOYEE
                         LONG-TERM SAVINGS PLAN - IBEW LOCAL NO. 702

                         By         /s/Donald E. Brandt 
                            -----------------------------------------------
                                     DONALD E. BRANDT 
                               Senior Vice President, Finance 
                                     Ameren Corporation

                                     II - 7
9

                                  EXHIBIT INDEX

Exhibit No.

   4.1       Article III of the Restated Certificate of Incorporation of the
             Registrant (incorporated by reference to Exhibit 3(i) of the Form
             S-4 Registration Statement of the Registrant, Reg. No. 33-64165).

   4.2       By-Laws of the Registrant (incorporated by reference to Annex G of
             the Joint Proxy Statement/Prospectus included in the Form S-4
             Registration Statement of the Registrant, Reg. No. 33-64165).

   5         Opinion of William E. Jaudes as to the legality of the securities
             being issued.

  23.1       Consent of Price Waterhouse LLP.

  23.2       Consent of Arthur Andersen LLP.

  23.3       Consent of William E. Jaudes (included in Exhibit 5).

  24         Powers of Attorney.

              All Exhibits are filed electronically with Form S-8.

                                     II - 8