UNITED STATES SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                   FORM 10-Q/A

[X]     QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
        EXCHANGE ACT OF 1934

                  For the Quarterly Period Ended June 30, 2003

                                       OR

[ ]     TRANSITION  REPORT  PURSUANT TO SECTION 13 OR 15(d) OF THE  SECURITIES
        EXCHANGE ACT OF 1934

<TABLE>
<CAPTION>


     Commission                 Name of Registrant; State of Incorporation;                  IRS Employer
     File Number                Address of Principal Executive Offices; and                  Identification
                                Telephone Number                                             Number
---------------------      ---------------------------------------------------------    ------------------------
<S>  <C>                                                                                     <C>
     1-16169                    EXELON CORPORATION                                           23-2990190
                                (a Pennsylvania corporation)
                                10 South Dearborn Street - 37th Floor
                                P.O. Box 805379
                                Chicago, Illinois 60680-5379
                                (312) 394-7398
     1-1839                     COMMONWEALTH EDISON COMPANY                                  36-0938600
                                (an Illinois corporation)
                                10 South Dearborn Street - 37th Floor
                                P.O. Box 805379
                                Chicago, Illinois 60680-5379
                                (312) 394-4321
     1-1401                     PECO ENERGY COMPANY                                          23-0970240
                                (a Pennsylvania corporation)
                                P.O. Box 8699 2301 Market Street
                                Philadelphia, Pennsylvania 19101-8699
                                (215) 841-4000
     333-85496                  EXELON GENERATION COMPANY, LLC                               23-3064219
                                (a Pennsylvania limited liability company)
                                300 Exelon Way
                                Kennett Square, Pennsylvania 19348
                                (610) 765-6900

</TABLE>


     Indicate  by check mark  whether the  registrant  (1) has filed all reports
required to be filed by Section 13 or 15(d) of the  Securities  Exchange  Act of
1934  during  the  preceding  12 months  (or for such  shorter  period  that the
registrant was required to file such reports),  and (2) has been subject to such
filing requirements for the past 90 days. Yes [X] No [_].

     The number of shares outstanding of each registrant's common stock as of
June 30, 2003 was:

     Exelon Corporation Common Stock, without par value              325,848,491
     Commonwealth Edison Company Common Stock, $12.50 par value      127,016,429
     PECO Energy Company Common Stock, without par value             170,478,507
     Exelon Generation Company, LLC                               not applicable

     Indicate by check mark whether the registrant is an  accelerated  filer (as
defined  in  Rule  12b-2  of  the  Act).  Exelon  Corporation  Yes  [X]  No  [ ]
Commonwealth Edison Company,  PECO Energy Company and Exelon Generation Company,
LLC Yes [ ] No [X].



<PAGE>



                                TABLE OF CONTENTS


                                                                 Page No.
                                                                 --------
      FILING FORMAT                                                  3
      EXPLANATORY NOTE                                               3

      PART I.   FINANCIAL INFORMATION                                4
      ITEM 4.   CONTROLS AND PROCEDURES                              4
      PART II.  OTHER INFORMATION                                    8
      ITEM 6.  EXHIBITS AND REPORTS ON FORM 8-K                      8

      SIGNATURES                                                    11





                                       2
<PAGE>



     FILING FORMAT
     This combined Form 10-Q/A is being filed  separately by Exelon  Corporation
(Exelon),  Commonwealth  Edison Company (ComEd),  PECO Energy Company (PECO) and
Exelon Generation Company, LLC (Generation) (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.

     EXPLANATORY NOTE
     Exelon,  ComEd,  PECO and Generation are filing this amendment on Form 10-Q
/A in  response  to  comments  received  from the  staff of the  Securities  and
Exchange Commission (SEC) in connection with its review of Exelon's Registration
Statement on Form S-3 (File No.  333-108546),  which incorporates this quarterly
report by reference.

     This amendment  makes changes to Part I, Item 4. Controls and Procedures to
confirm that each Registrant's  disclosure controls and procedures are effective
and to clarify that each Registrant's access and ability to apply its disclosure
controls and  procedures to entities that it does not control or manage are more
limited than subsidiaries that it controls and manages.

     Unless otherwise stated, all information  contained in this amendment is as
of July 30, 2003, the filing date of our original  Quarterly Report on Form 10-Q
for the quarter ended June 30, 2003.



                                       3
<PAGE>


     PART I.          FINANCIAL INFORMATION
     ITEM 4.          CONTROLS AND PROCEDURES

     Exelon

     During  the second  quarter of 2003,  Exelon's  management,  including  the
principal executive officer and principal financial officer,  evaluated Exelon's
disclosure  controls  and  procedures  related  to  the  recording,  processing,
summarization  and reporting of information in Exelon's periodic reports that it
files with the SEC. These disclosure  controls and procedures have been designed
to ensure  that (a)  material  information  relating  to Exelon,  including  its
consolidated subsidiaries, is made known to Exelon's management, including these
officers,  by other  employees  of  Exelon  and its  subsidiaries,  and (b) this
information  is recorded,  processed,  summarized,  evaluated and  reported,  as
applicable,  within the time periods specified in the SEC's rules and forms. Due
to the inherent  limitations of control systems,  not all  misstatements  may be
detected.  These  inherent  limitations  include the realities that judgments in
decision-making  can be faulty and that  breakdowns  can occur because of simple
error or mistake. Additionally, controls could be circumvented by the individual
acts of some persons or by collusion  of two or more people.  Exelon's  controls
and procedures  can only provide  reasonable,  not absolute,  assurance that the
above objectives have been met. Exelon does not control or manage certain of its
unconsolidated  entities and thus its access and ability to apply its disclosure
controls and  procedures to entities that it does not control or manage are more
limited than is the case for the subsidiaries it controls and manages.

     Accordingly,  as of June 30,  2003,  these  officers  (principal  executive
officer and principal  financial  officer)  concluded  that Exelon's  disclosure
controls and procedures were effective to accomplish  their  objectives.  Exelon
continually strives to improve its disclosure controls and procedures to enhance
the quality of its  financial  reporting  and to maintain  dynamic  systems that
change as conditions warrant.

     In the second  quarter of 2003,  Exelon  implemented  a new general  ledger
accounting  system.  The new general  ledger system was  implemented in order to
provide a consistent  system platform for the affiliated Exelon companies and to
enhance management reporting and analysis. This change in systems was subject to
thorough  testing and review by internal  and  external  parties both before and
after final  implementation.  Exelon continually strives to improve its internal
control over financial  reporting to provide reasonable  assurance regarding the
reliability of financial  reporting and the preparation of financial  statements
for  external  purposes  in  accordance  with  generally   accepted   accounting
principles (GAAP).

     ComEd

     During  the second  quarter  of 2003,  ComEd's  management,  including  the
principal executive officer and principal  financial officer,  evaluated ComEd's
disclosure  controls  and  procedures  related  to  the  recording,  processing,
summarization  and reporting of information in ComEd's  periodic reports that it
files with the SEC. These disclosure  controls and procedures have been designed
to  ensure  that (a)  material  information  relating  to ComEd,  including  its
consolidated subsidiaries, is made known to ComEd's management,  including these
officers,  by  other  employees  of  ComEd  and its  subsidiaries,  and (b) this
information  is recorded,  processed,


                                       4
<PAGE>


summarized,  evaluated  and  reported,  as  applicable,  within the time periods
specified  in the SEC's  rules and forms.  Due to the  inherent  limitations  of
control  systems,  not  all  misstatements  may  be  detected.   These  inherent
limitations  include the  realities  that  judgments in  decision-making  can be
faulty  and that  breakdowns  can  occur  because  of simple  error or  mistake.
Additionally,  controls could be  circumvented  by the  individual  acts of some
persons or by collusion of two or more people.  ComEd's  controls and procedures
can only provide reasonable,  not absolute,  assurance that the above objectives
have been met.  ComEd does not control or manage  certain of its  unconsolidated
entities  and thus its access and ability to apply its  disclosure  controls and
procedures  to entities that it does not control or manage are more limited than
is the case for the subsidiaries it controls and manages.

     Accordingly,  as of June 30,  2003,  these  officers  (principal  executive
officer and  principal  financial  officer)  concluded  that ComEd's  disclosure
controls and procedures  were effective to accomplish  their  objectives.  ComEd
continually strives to improve its disclosure controls and procedures to enhance
the quality of its  financial  reporting  and to maintain  dynamic  systems that
change as conditions warrant.

     In the second  quarter of 2003,  ComEd  implemented  a new  general  ledger
accounting  system.  The new general  ledger system was  implemented in order to
provide a consistent  system platform for the affiliated Exelon companies and to
enhance management reporting and analysis. This change in systems was subject to
thorough  testing and review by internal  and  external  parties both before and
after final  implementation.  ComEd continually  strives to improve its internal
control over financial  reporting to provide reasonable  assurance regarding the
reliability of financial  reporting and the preparation of financial  statements
for external purposes in accordance with GAAP.

     PECO

     During  the  second  quarter  of 2003,  PECO's  management,  including  the
principal  executive officer and principal  financial officer,  evaluated PECO's
disclosure  controls  and  procedures  related  to  the  recording,  processing,
summarization  and reporting of information in PECO's  periodic  reports that it
files with the SEC. These disclosure  controls and procedures have been designed
to  ensure  that  (a)  material  information  relating  to PECO,  including  its
consolidated subsidiaries,  is made known to PECO's management,  including these
officers,  by  other  employees  of PECO  and  its  subsidiaries,  and (b)  this
information  is recorded,  processed,  summarized,  evaluated and  reported,  as
applicable,  within the time periods specified in the SEC's rules and forms. Due
to the inherent  limitations of control systems,  not all  misstatements  may be
detected.  These  inherent  limitations  include the realities that judgments in
decision-making  can be faulty and that  breakdowns  can occur because of simple
error or mistake. Additionally, controls could be circumvented by the individual
acts of some persons or by collusion of two or more people.  PECO's controls and
procedures can only provide reasonable,  not absolute,  assurance that the above
objectives  have  been met.  PECO does not  control  or  manage  certain  of its
unconsolidated  entities and thus its access and ability to apply its disclosure
controls and  procedures to entities that it does not control or manage are more
limited than is the case for the subsidiaries it controls and manages.



                                       5
<PAGE>


     Accordingly,  as of June 30,  2003,  these  officers  (principal  executive
officer and  principal  financial  officer)  concluded  that  PECO's  disclosure
controls and procedures  were  effective to accomplish  their  objectives.  PECO
continually strives to improve its disclosure controls and procedures to enhance
the quality of its  financial  reporting  and to maintain  dynamic  systems that
change as conditions warrant.

     In the second  quarter  of 2003,  PECO  implemented  a new  general  ledger
accounting  system.  The new general  ledger system was  implemented in order to
provide a consistent  system platform for the affiliated Exelon companies and to
enhance management reporting and analysis. This change in systems was subject to
thorough  testing and review by internal  and  external  parties both before and
after final  implementation.  PECO  continually  strives to improve its internal
control over financial  reporting to provide reasonable  assurance regarding the
reliability of financial  reporting and the preparation of financial  statements
for external purposes in accordance with GAAP.

     Generation

     During the second quarter of 2003, Generation's  management,  including the
principal   executive  officer  and  principal   financial  officer,   evaluated
Generation's  disclosure  controls  and  procedures  related  to the  recording,
processing,  summarization and reporting of information in Generation's periodic
reports that it files with the SEC.  These  disclosure  controls and  procedures
have  been  designed  to  ensure  that  (a)  material  information  relating  to
Generation,   including  its  consolidated   subsidiaries,   is  made  known  to
Generation's  management,  including  these  officers,  by  other  employees  of
Generation  and  its  subsidiaries,   and  (b)  this  information  is  recorded,
processed,  summarized,  evaluated and reported, as applicable,  within the time
periods specified in the SEC's rules and forms. Due to the inherent  limitations
of control  systems,  not all  misstatements  may be  detected.  These  inherent
limitations  include the  realities  that  judgments in  decision-making  can be
faulty  and that  breakdowns  can  occur  because  of simple  error or  mistake.
Additionally,  controls could be  circumvented  by the  individual  acts of some
persons  or by  collusion  of two or  more  people.  Generation's  controls  and
procedures can only provide reasonable,  not absolute,  assurance that the above
objectives  have been met.  Generation does not control or manage certain of its
unconsolidated  entities and thus its access and ability to apply its disclosure
controls and  procedures to entities that it does not control or manage are more
limited than is the case for the subsidiaries it controls and manages.

     Accordingly,  as of June 30,  2003,  these  officers  (principal  executive
officer and principal financial officer) concluded that Generation's  disclosure
controls  and  procedures  were  effective  to  accomplish   their   objectives.
Generation continually strives to improve its disclosure controls and procedures
to enhance  the  quality of its  financial  reporting  and to  maintain  dynamic
systems that change as conditions warrant.



                                       6
<PAGE>


     In the second quarter of 2003, Generation  implemented a new general ledger
accounting  system.  The new general  ledger system was  implemented in order to
provide a consistent  system platform for the affiliated Exelon companies and to
enhance management reporting and analysis. This change in systems was subject to
thorough  testing and review by internal  and  external  parties both before and
after  final  implementation.  Generation  continually  strives to  improve  its
internal  control  over  financial  reporting  to provide  reasonable  assurance
regarding  the  reliability  of  financial  reporting  and  the  preparation  of
financial statements for external purposes in accordance with GAAP.






                                       7
<PAGE>


     PART II.         OTHER INFORMATION
     ITEM 6.          EXHIBITS AND REPORTS ON FORM 8-K

     (a) Exhibits:

           4-1 -  Indenture to Subordinated Debt Securities dated as of June
                  24, 2003 between PECO Energy Company, as Issuer, and Wachovia
                  Bank National Association, as Trustee.*

           4-2 -  Preferred Securities Guarantee Agreement between PECO Energy
                  Company, as Guarantor, and Wachovia Trust Company, National
                  Association, as Trustee, dated as of June 24, 2003.*

           4-3 -  PECO Energy Capital Trust IV Amended and Restated
                  Declaration of Trust among PECO Energy Company, as Sponsor,
                  Wachovia Trust Company, National Association, as Delaware
                  Trustee and Property Trustee, and J. Barry Mitchell, George R.
                  Shicora and Charles S. Walls as Administrative Trustees dated
                  as of June 24, 2003.*

        Certifications   Pursuant  to  Rule   13a-14(a)  and  15d-14(a)  of  the
        Securities  and Exchange Act of 1934 as to the Quarterly  Report on Form
        10-Q/A  for the  quarterly  period  ended  June  30,  2003  filed by the
        following officers for the following companies:

   -----------------------------------------------------------------------------
   31-1  -  Filed by John W. Rowe for Exelon Corporation
   31-2  -  Filed by Robert S. Shapard for Exelon Corporation
   31-3  -  Filed by Michael B. Bemis for Commonwealth Edison Company
   31-4  -  Filed by J. Barry Mitchell for Commonwealth Edison Company
   31-5  -  Filed by Michael B. Bemis for PECO Energy Company
   31-6  -  Filed by J. Barry Mitchell for PECO Energy Company
   31-7  -  Filed by Oliver D. Kingsley Jr. for Exelon Generation Company, LLC
   31-8  -  Filed by J. Barry Mitchell for Exelon Generation Company, LLC
   -----------------------------------------------------------------------------

   Certifications Pursuant to Section 1350 of Chapter 63 of Title 18
   United States Code (Sarbanes - Oxley Act of 2002) as to the Quarterly
   Report on Form 10-Q for the quarterly period ended June 30, 2003
   filed by the following officers for the following companies:*
   -----------------------------------------------------------------------------
   32-1  -    Filed by John W. Rowe for Exelon Corporation
   32-2  -    Filed by Robert S. Shapard for Exelon Corporation
   32-3  -    Filed by Michael B. Bemis for Commonwealth Edison Company
   32-4  -    Filed by Robert S. Shapard for Commonwealth Edison Company
   32-5  -    Filed by Michael B. Bemis for PECO Energy Company
   32-6  -    Filed by Robert S. Shapard for PECO Energy Company
   32-7  -    Filed by Oliver D. Kingsley Jr. for Exelon Generation Company, LLC
   32-8  -    Filed by Robert S. Shapard for Exelon Generation Company, LLC
   -----------------------------------------------------------------------------

     * Exhibits were filed with the Form 10-Q for the quarterly period ended
     June 30, 2003 filed on July 30, 2003 (File No. 1-16169, June 30, 2003 Form
     10-Q, Exhibits 4-1 through 32-8).



                                       8
<PAGE>


      (b)     Reports on Form 8-K:

     Exelon,  ComEd,  PECO and/or  Generation  filed Current Reports on Form 8-K
during the three months ended June 30, 2003 regarding the following items:

<TABLE>
<CAPTION>

              Date of Earliest
              Event Reported            Description of Item Reported
------------------------------------------------------------------------------------------------------------
<S>                 <C>                       <C>
              April 3, 2003             "ITEM 9.  REGULATION FD DISCLOSURE"  filed for Exelon,  ComEd,  PECO
                                        and Generation  regarding a presentation  by John W. Rowe,  Chairman
                                        and CEO, at the  Berenson & Company and The Williams  Capital  Group
                                        Midwest  Utilities  Seminar.  The  exhibits  include the slides used
                                        during the presentation.

              April 7, 2003             "ITEM 5. OTHER  EVENTS"  filed by ComEd  regarding  the  issuance of
                                        $395 million in First Mortgage Bonds.

              April 28, 2003            "ITEM 9. REGULATION FD DISCLOSURE"  filed under Item 9 in compliance
                                        with Item 12 for Exelon,  ComEd,  PECO and Generation  regarding the
                                        first quarter 2003 earnings  release and items discussed  during the
                                        earnings  conference  call.  Also  included  as an  exhibit  to this
                                        report  was  a new  release  regarding  the  "Exelon  Way"  business
                                        model.

              May 2, 2003               "ITEM 5.  OTHER  EVENTS"  filed  for  Exelon  regarding  Richard  H.
                                        Glanton's  acceptance  of the  position  of Senior  Vice  President,
                                        Corporate  Development and his relinquishment of his directorship on
                                        the Exelon Board.

              May 7, 2003               "ITEM 5.  OTHER  EVENTS"  filed  for  Exelon,  PECO  and  Generation
                                        announcing that the U.S. Nuclear  Regulatory  Commission  approved a
                                        20-year  extension of the  operating  licenses for Exelon  Nuclear's
                                        Peach Bottom Atomic Power Station.

              May 20, 2003              "ITEM 9.  REGULATION  FD  DISCLOSURE"  filed for Exelon  regarding a
                                        presentation  by Robert S.  Shapard,  Executive  Vice  President and
                                        CFO.  The exhibit includes the slides used during the presentation.

              May 29, 2003              "ITEM 5. OTHER  EVENTS" filed for Exelon and  Generation  announcing
                                        the issuance of a call notice for the  remaining  50.1%  interest in
                                        Sithe Energies, Inc.

              June 2, 2003              "ITEM 5. OTHER EVENTS" filed for Exelon and  Generation  regarding a
                                        request  for an  amendment  to the  Exelon  Boston  Generating,  LLC
                                        credit facility and the  construction of the Mystic 8 and 9 and Fore
                                        River generating units.

              June 2, 2003              "ITEM 5. OTHER  EVENTS"  filed for Exelon and  Generation  regarding
                                        the approval of an amendment to the Exelon  Boston



                                       9
<PAGE>


                                        Generating,  LLC credit facility.

              June 11, 2003             "ITEM 9.  REGULATION FD DISCLOSURE"  filed for Exelon,  ComEd,  PECO
                                        and  Generation  regarding  a  presentation  by Robert  S.  Shapard,
                                        Executive  Vice  President and CFO. The exhibits  include the slides
                                        and handouts used during the presentation.

              June 13, 2003             "ITEM 5. OTHER EVENTS"  filed for Exelon  regarding the dismissal of
                                        a class action lawsuit.

              June 18, 2003             "ITEM 5. OTHER EVENTS"  filed for Exelon  announcing an agreement to
                                        sell certain businesses of its subsidiary InfraSource, Inc.

              June 18, 2003             "ITEM  5.  OTHER   EVENTS"  filed  for  Exelon,   ComEd,   PECO  and
                                        Generation  regarding the sale of certain businesses of InfraSource,
                                        Inc.

              June 25, 2003             "ITEM 5. OTHER  EVENTS"  filed for  Exelon,  ComEd,  and  Generation
                                        regarding  the  exercise  of  Generation's   call  option  under  an
                                        existing purchase power agreement with Midwest Generation, LLC.
------------------------------------------------------------------------------------------------------------


</TABLE>




                                       10
<PAGE>


                                   SIGNATURES
--------------------------------------------------------------------------------

              Pursuant to 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.

                               EXELON CORPORATION

     /s/ John W. Rowe                             /s/ Robert S. Shapard
     ----------------------------                 -----------------------------
     JOHN W. ROWE                                 ROBERT S. SHAPARD
     Chairman and                                 Executive Vice President and
     Chief Executive Officer                      Chief Financial Officer
     (Principal Executive Officer)                (Principal Financial Officer)

     /s/ Matthew F. Hilzinger
     ---------------------------------------
     MATTHEW F. HILZINGER
     Vice President and Corporate Controller
     (Principal Accounting Officer)

     December 15, 2003

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

              Pursuant to 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.

                           COMMONWEALTH EDISON COMPANY

     /s/ Michael B. Bemis                       /s/ J. Barry Mitchell
     ---------------------------------          -------------------------------
     MICHAEL B. BEMIS                           J. BARRY MITCHELL
     President, Exelon Energy Delivery          Chief Financial Officer
     (Principal Executive Officer)              (Principal Financial Officer)


     /s/ Duane M. DesParte                      /s/ Frank M. Clark
     ------------------------------             --------------------------------
     DUANE M. DESPARTE                          FRANK M. CLARK
     Vice President and Controller,             President, ComEd
     Exelon Energy Delivery
     (Principal Accounting Officer)

      December 15, 2003



                                       11
<PAGE>

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

              Pursuant to 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.

                               PECO ENERGY COMPANY

     /s/ Michael B. Bemis                       /s/ J. Barry Mitchell
     ---------------------------------          -------------------------------
     MICHAEL B. BEMIS                           J. BARRY MITCHELL
     President, Exelon Energy Delivery          Chief Financial Officer
     (Principal Executive Officer)              (Principal Financial Officer)


     /s/ Duane M. DesParte                      /s/ Denis P. O'Brien
     ------------------------------             --------------------
     DUANE M. DESPARTE                          DENIS P. O'BRIEN
     Vice President and Controller,             President, PECO
     Exelon Energy Delivery
     (Principal Accounting Officer)

      December 15, 2003

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


              Pursuant to 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.

                         EXELON GENERATION COMPANY, LLC

     /s/ Oliver D. Kingsley Jr.                 /s/ J. Barry Mitchell
     ----------------------------               -------------------------------
     OLIVER D. KINGSLEY JR.                     J. BARRY MITCHELL
     Chief Executive Officer and                Chief Financial Officer
     President                                  (Principal Financial Officer)
     (Principal Executive Officer)


     /s/ Matthew F. Hilzinger
     -----------------------------------------------
     MATTHEW F. HILZINGER
     Vice President and Corporate Controller, Exelon
     (Principal Accounting Officer)


      December 15, 2003



                                       12