Exhibit 4.1

                               FIRST AMENDMENT TO
                      AMENDED AND RESTATED TRUST AGREEMENT

      FIRST AMENDMENT to Amended and Restated Trust Agreement (the "Amendment"),
dated as of March  24,  2004,  among  (i)  BancFirst  Corporation,  an  Oklahoma
corporation  (including any successors or assigns,  the  "Depositor");  (ii) The
Bank of New York, a New York banking corporation,  as property trustee, (in such
capacity, the "Property Trustee");  (iii) David E. Rainbolt, an individual;  Joe
T. Shockley,  Jr., an individual;  and Randy P. Foraker, an individual;  each of
whose  address is c/o  BancFirst  Corporation,  101 North  Broadway,  Suite 800,
Oklahoma City, Oklahoma 73102 (each an "Administrative Trustee" and collectively
the "Administrative Trustees").

WITNESSETH

      WHEREAS,  the  Depositor,  the  Property  Trustee,  The  Bank of New  York
(Delaware),  as Delaware trustee,  and each of the Administrative  Trustees have
heretofore  entered into that certain Amended and Restated Trust Agreement dated
February 26, 2004 (the "Amended and Restated Trust Agreement"); and

      WHEREAS,  the second recital to the Amended and Restated  Trust  Agreement
stated  that the  purpose of such  agreement  was to provide  for,  among  other
things, the issuance and sale of the "Preferred Securities" by BFC Capital Trust
II (the "Trust")  pursuant to that certain  Underwriting  Agreement  dated as of
February 23, 2004,  among the Trust, the Depositor,  and Advest,  Inc., and Howe
Barnes Investments, Inc., as the Underwriters; and

      WHEREAS,  pursuant  to  Section  1  of  the  Underwriting  Agreement,  the
Preferred  Securities  included  both "Firm  Securities,"  defined as  Preferred
Securities having an aggregate  liquidation  amount of $25,000,000,  and "Option
Securities,"  having an  aggregate  liquidation  amount  of up to an  additional
$1,000,000; and

      WHEREAS,  the Amended and Restated Trust  Agreement  provided only for the
issuance and sale of Preferred  Securities that  constituted  "Firm  Securities"
under the  Underwriting  Agreement  (defined in the  Underwriting  Agreement  as
Preferred  Securities  having an aggregate  liquidation  amount of $25,000,000),
notwithstanding  the stated intention of the parties to provide for the issuance
and sale of  Preferred  Securities  "pursuant  to the  Underwriting  Agreement,"
conformity  with which would have required  that the Amended and Restated  Trust
Agreement  provide for the  additional  possible  issuance and sale of Preferred
Securities  constituting  "Option  Securities,"  as defined in the  Underwriting
Agreement; and

      WHEREAS,  pursuant to Section  10.2(a) of the Amended and  Restated  Trust
Agreement,  the Amended and Restated Trust Agreement may be amended from time to
time by the Property  Trustee,  the  Administrative  Trustees and the Depositor,
without the consent of any  Securityholders  (as defined  therein),  to cure any
ambiguity, correct or supplement any provision therein which may be inconsistent
with any other provision  therein,  or to make any other provisions with respect
to matters or questions  arising under the Amended and Restated Trust Agreement,
so long as any such amendment is not  inconsistent  with the other provisions of
the Amended and Restated Trust Agreement; and

      WHEREAS, the parties hereto desire to amend the Amended and Restated Trust
Agreement to provide for the additional  possible issuance and sale of Preferred
Securities  constituting "Option Securities" in conformity with the terms of the
Underwriting Agreement, as contained herein;


                                                                     Exhibit 4.1

      NOW THEREFORE,  in  consideration  of the agreements and  obligations  set
forth herein and for other good and valuable  consideration,  the sufficiency of
which is hereby  acknowledged,  each party, for the benefit of the other parties
and for the benefit of the Holders, hereby agrees as follows:

      1.    Definitions.  Capitalized  terms used herein and not defined  herein
shall  have the  respective  meanings  given to such  terms in the  Amended  and
Restated Trust Agreement.

      2.    Amendments to the Amended and Restated Trust Agreement.

            (a)   Section  1.1  is  hereby  amended  to  include  the  following
                  definitions:

                  "Option  Closing Date" shall have the meaning  provided in the
                  Underwriting Agreement.

                  "Option  Securities" means an aggregate  Liquidation Amount of
                  up  to  $1,000,000  of  the  Trust's  7.20%  Cumulative  Trust
                  Preferred Securities,  issuable to the Underwriters,  at their
                  option,  exercisable  within  30 days  after  the  date of the
                  Underwriting  Agreement,  solely to cover over-allotments,  if
                  any.

            (b)   Section  2.4(a) is hereby  amended to read in its  entirety as
                  follows:

                  (a) The Depositor and an Administrative  Trustee, on behalf of
                  the Trust and pursuant to the Trust  Agreement,  have executed
                  and delivered the  Underwriting  Agreement.  Contemporaneously
                  with the  execution and delivery of this Trust  Agreement,  an
                  Administrative  Trustee, on behalf of the Trust, shall execute
                  in accordance with Section 5.2 and deliver to the Underwriters
                  named  in the  Underwriting  Agreement,  Preferred  Securities
                  Certificates,  registered  in the name of the  nominee  of the
                  initial Clearing Agency, as instructed by Advest,  Inc., as an
                  Underwriter,  in an aggregate  amount of  1,000,000  Preferred
                  Securities   having  an   aggregate   Liquidation   Amount  of
                  $25,000,000,  against receipt of such aggregate purchase price
                  of such Preferred  Securities of $25,000,000  which amount the
                  Administrative  Trustee shall promptly deliver to the Property
                  Trustee. At the option of the Underwriters,  within 30 days of
                  the date of the  Underwriting  Agreement,  and  solely for the
                  purpose   of   covering   an   over-allotment,   if  any,   an
                  Administrative  Trustee, on behalf of the Trust, shall execute
                  in accordance with Section 5.2 and deliver to the Underwriters
                  named  in the  Underwriting  Agreement,  Preferred  Securities
                  Certificates,  registered  in the name of the  nominee  of the
                  initial Clearing Agency, as instructed by Advest,  Inc., as an
                  Underwriter,  in an  aggregate  amount of up to 40,000  Option
                  Securities  having an  aggregate  Liquidation  Amount of up to
                  $1,000,000,  against receipt of such aggregate  purchase price
                  of such Option Securities of up to $1,000,000 which amount the
                  Administrative  Trustee shall promptly deliver to the Property
                  Trustee.

            (c)   Section  2.5 is  hereby  amended  to read in its  entirety  as
                  follows:

                  Contemporaneously  with the  execution  and  delivery  of this
                  Trust Agreement,  an Administrative  Trustee, on behalf of the
                  Trust,  shall  execute  in  accordance  with  Section  5.2 and
                  deliver  to  the  Depositor  Common  Securities  Certificates,
                  registered  in the  name  of the  Depositor,  in an  aggregate
                  amount of 30,928 Common Securities having an


                                                                     Exhibit 4.1

                  aggregate  Liquidation Amount of $773,200,  against payment by
                  the Depositor of such amount, which amount such Administrative
                  Trustee shall promptly deliver to the Property Trustee. In the
                  event of any exercise of an  over-allotment  option  requiring
                  issuance of additional Preferred Securities  Certificates,  as
                  described  in Section  2.4 above,  a  proportionate  number of
                  additional Common Securities Certificates,  with corresponding
                  aggregate  Liquidation  Amount,  shall  be  delivered  to  the
                  Depositor.  An Administrative Trustee, on behalf of the Trust,
                  shall subscribe to and purchase from the Depositor Debentures,
                  registered  in the name of the  Property  Trustee on behalf of
                  the Trust,  and having an aggregate  principal amount equal to
                  $25,773,200  (plus,  in  the  event  of  any  exercise  of the
                  over-allotment option (i) a corresponding additional number of
                  Debentures  not  exceeding  an aggregate  principal  amount of
                  $1,000,000 and (ii) a  corresponding  number of Debentures not
                  exceeding an aggregate principal amount equal to the aggregate
                  Liquidation  Amount of Common  Securities  issued  pursuant to
                  such   exercise   of  an   over-allotment   option)   and,  in
                  satisfaction  of the purchase price for such  Debentures,  the
                  Property Trustee, on behalf of the Trust, shall deliver to the
                  Depositor the sum of $25,773,200, such amount being the sum of
                  the amounts  delivered to the Property Trustee pursuant to (a)
                  the second  sentence of Section 2.4 and (b) the first sentence
                  of this Section  2.5,  plus any  corresponding  over-allotment
                  option amount  (being the sum of the amounts  delivered to the
                  Property Trustee pursuant to (i) the third sentence of Section
                  2.4, and (ii) the second sentences of this Section 2.5).

            (d)   Section  5.3 is  hereby  amended  to read in its  entirety  as
                  follows:

                  On  the  Closing  Date  (and,   with  respect  to  the  Option
                  Securities,  on the Option Closing Date),  the  Administrative
                  Trustees  shall cause  Trust  Securities  Certificates,  in an
                  aggregate  Liquidation  Amount as  provided in Section 2.4 and
                  Section  2.5,  to be  executed  on  behalf  of the  Trust  and
                  delivered  to or upon  the  written  order  of the  Depositor,
                  signed by its chief  executive  officer,  its  president,  any
                  executive vice president or any vice  president,  treasurer or
                  assistant  treasurer or controller  without further  corporate
                  action by the Depositor, in authorized denominations.

      3.    Counterparts.   This   Amendment   may  be   executed   in   several
counterparts,  each of which  when  executed  and  delivered  shall be deemed an
original and all of which counterparts, taken together, shall constitute but one
and the same Amendment.

      4.    Governing Law. THIS AMENDMENT  SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF DELAWARE.

      5.    Amended and Restated Trust  Agreement  Remains in Effect.  Except as
provided  herein,  all  provisions,  terms and  conditions  of the  Amended  and
Restated  Trust  Agreement  shall  remain in full force and  effect.  As amended
hereby,  the Amended and Restated  Trust  Agreement is ratified and confirmed in
all respects.

                     [Signatures Provided on Following Page]

                                                                     Exhibit 4.1

      IN WITNESS  WHEREOF,  the parties  hereto have caused this Amendment to be
executed and delivered by their duly authorized  officers as of the day and year
first above written.

BancFirst Corporation

By:  /s/ Joe T. Shockley, Jr.                /s/ David E. Rainbolt
    -----------------------------------      -----------------------------------
    Name:  Joe T. Shockley, Jr.              Name: David E. Rainbolt,
    Title: Executive Vice President and            as Administrative Trustee
           Chief Financial Officer

The Bank of New York,                         /s/ Joe T. Shockley, Jr.
as Property Trustee                          -----------------------------------
                                             Name: Joe T. Shockley, Jr.
                                                   as Administrative Trustee

By: /s/ Van K. Brown                         /s/ Randy P. Foraker
    -----------------------------------      -----------------------------------
    Name:  Van K. Brown                      Name: Randy P. Foraker,
    Title: Vice President                          as Administrative Trustee