EXHIBIT 99.3
                               Offer to Exchange
                     7.75% Senior Notes, Series C due 2005,
                          for any and all outstanding
                     7.75% Senior Notes, Series A due 2005
                                      and
                     8.35% Senior Notes, Series D due 2010
                          for any and all outstanding
                     8.35% Senior Notes, Series B due 2010
                       of AmerenEnergy Generating Company

To The Depository Trust Company Participants:

     We are enclosing herewith the materials listed below relating to the offer
by AmerenEnergy Generating Company, an Illinois corporation (the "Company"), to
exchange, in an offering registered under the Securities Act of 1933, as amended
(the "Securities Act"), (i) up to $225,000,000 aggregate principal amount of its
7.75% Senior Notes, Series C due 2005 (the "Series C Exchange Notes"), for an
equal principal amount of 7.75% Senior Notes, Series A due 2005 (the "Series A
Notes"), and (ii) up to $200,000,000 aggregate principal amount of its 8.35%
Senior Notes, Series D due 2010 (together with the Series C Exchange Notes, the
"Exchange Notes"), for an equal principal amount of 8.35% Senior Notes, Series B
due 2010 (together with the Series A Notes, the "Old Notes"), upon the terms and
subject to the conditions set forth in the Prospectus dated                ,
2001 (as amended or supplemented from time to time, the "Prospectus") of the
Company and the related Letter of Transmittal (as amended or supplemented from
time to time, the "Letter of Transmittal"), which together constitute the
Company's offer (the "Exchange Offer").

     Enclosed herewith are copies of the following documents:

          1.   Prospectus dated                   , 2001;

          2.   Letter of Transmittal;

          3.   Notice of Guaranteed Delivery;

          4.   Letter that may be sent to your clients for whose account you
               hold Old Notes in your name or in the name of your nominee, to
               accompany the instruction form referred to below, for obtaining
               such client's instruction with regard to the Exchange Offer; and

          5.   Instructions to Registered Holder and/or Book-Entry Transfer
               Participant from Owner.

     We urge you to contact your clients promptly.  Please note that the
Exchange Offer will expire at 5:00 p.m., New York City time, on                ,
2001 (the "Expiration Date"), unless extended.

     The Exchange Offer is not conditioned upon any minimum number of Old Notes
being tendered.

     To tender in the Exchange Offer, a holder must cause to be transmitted an
Agent's Message (as defined below) in connection with a book-entry transfer and
mail or otherwise deliver the Agent's Message to Ameren Services Company (the
"Exchange Agent"), prior to 5:00 p.m., New York City time, on the Expiration
Date. To be tendered effectively, the Agent's Message must be completed and
received by the Exchange Agent at the address set forth in the Letter of
Transmittal prior to 5:00 p.m., New York City time, on the Expiration Date.
Confirmation of book-entry transfer must be received by the Exchange Agent prior
to the Expiration Date.

     The term "Agent's Message" means a message, transmitted by a book-entry
transfer facility to, and received by, the Exchange Agent, forming a part of a
confirmation of a book-entry, which states that such book-entry transfer
facility has received an express acknowledgment from the participant in such
book-entry transfer facility tendering the Old Notes that such participant has
received and agrees:  (i) to participate in the Automated Tender Option Program
("ATOP"); (ii) to be bound by the terms of the Letter of Transmittal; and (iii)
that the Company may enforce such agreement against such participant.


     Pursuant to the Letter of Transmittal, each holder will represent to the
Company that (i) neither it nor any person receiving the Exchange Notes through
it is an "affiliate" of the Company (within the meaning of Rule 405 under the
Securities Act), (ii) it is not a broker-dealer tendering Old Notes acquired
directly from the Company, (iii) the Exchange Notes are to be acquired by it or
any other person receiving Exchange Notes through it, whether or not such person
is the holder, in the ordinary course of business, (iv) neither it nor any
person receiving the Exchange Notes through it (other than a broker-dealer
referred to in the next paragraph) is engaging, or intends to engage, in the
distribution of the Exchange Notes, (v) neither it nor any person receiving the
Exchange Notes through it has any arrangement or understanding with any person
to participate in the distribution of the Exchange Notes and (vi) it, on behalf
of itself and any other person receiving Exchange Notes through it, acknowledges
that if it or any such other person is deemed to have participated in the
Exchange Offer for the purpose of distributing the Exchange Notes, it and any
such other person must comply with the registration and prospectus delivery
requirements of the Securities Act in connection with any resale of the Exchange
Notes and cannot rely on the interpretations by the staff of the Securities and
Exchange Commission set forth in certain no-action letters that were issued to
third parties in similar transactions and on which the Company is relying in
making the Exchange Offer.

     Each participating broker-dealer that receives Exchange Notes for its own
account in exchange for Old Notes must acknowledge that it (i) acquired the Old
Notes for its own account as a result of market-making activities or other
trading activities, (ii) has not entered into any arrangement or understanding
with the Company or any "affiliate" of the Company (within the meaning of Rule
405 under the Securities Act) to distribute the Exchange Notes to be received in
the Exchange Offer and (iii) will deliver a prospectus meeting the requirements
of the Securities Act in connection with any resale of such Exchange Notes.  By
acknowledging that it will deliver a prospectus meeting the requirements of the
Securities Act in connection with any resale of such Exchange Notes, such
broker-dealer will not be deemed to admit that it is an "underwriter" within the
meaning of the Securities Act.

     The enclosed Instructions to Registered Holder and/or Book-Entry Transfer
Participant from Owner contain an authorization by the beneficial owners of the
Old Notes for you to make the foregoing representations.

     The Company will not pay any fee or commission to any broker or dealer or
to any other person (other than the Exchange Agent) in connection with the
solicitation of tenders of Old Notes pursuant to the Exchange Offer.  The
Company will not pay or cause to be paid any transfer taxes payable on the
transfer of Old Notes to it.

     Additional copies of the enclosed material may be obtained by contacting
Morrow & Co., Inc., the Information Agent for the Exchange Offer, at 445 Park
Avenue, 5th Floor, New York, New York 10022, Attention: John Ferguson, Personal
and Confidential.

                                 Very truly yours,

                                 AmerenEnergy Generating Company

                                 By:

     NOTHING CONTAINED HEREIN OR IN THE ENCLOSED DOCUMENTS SHALL CONSTITUTE YOU
THE AGENT OF AMERENENERGY GENERATING COMPANY OR AMEREN SERVICES COMPANY, OR
AUTHORIZE YOU TO USE ANY DOCUMENT OR MAKE ANY STATEMENT ON THEIR BEHALF IN
CONNECTION WITH THE EXCHANGE OFFER OTHER THAN THE DOCUMENTS ENCLOSED HEREWITH
AND THE STATEMENTS CONTAINED THEREIN.

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