Exhibit 99 (b)
    

Simmons First National Corporation
P. O. Box 7009
Pine Bluff, Arkansas 71611


Gentlemen:

   
     I may presently be considered to be an "affiliate", as defined in paragraph
(a) of Rule 144 of the Rules and  Regulations  of the  Securities  and  Exchange
commission  ("SEC") under the Securities Act of 1933, as amended (the "Act"), of
NBC Bank Corp.,  El Dorado,  Arkansas,  a bank holding  company  ("NBC Corp.").
Pursuant to the merger (the  "Merger") of NBC Corp.  with and into Simmons First
National Corporation ("Simmons"),  I will acquire _________ shares of the common
stock,  par value $1 per share  ("Common  Stock"),  of Simmons.  I represent and
warrant  that I will not make any sale,  transfer  or other  disposition  of the
Shares in violation of the Act or the General Rules and Regulations  promulgated
thereunder by the SEC.

         I have been advised that the Shares issued to me pursuant to the Merger
have been  registered  under the Act in the  Registration  Statement on SEC Form
S-4, as amended, Registration No.  333-76921("Registration  Statement") as filed
with the SEC, and have received a copy of the proxy/prospectus  filed as part of
the Registration  Statement.  However,  I have also been advised that any public
offering or sale by me of any of the Shares will,  under  current  law,  require
either (i) the further registration (by amendment of such Form S-4 or otherwise)
under  the  Act of the  Shares  to be  sold or (ii)  compliance  with  Rule  145
promulgated  under the Act or (iii) the  availability of another  exemption from
such registration.

     I agree that  notwithstanding  any  provision  herein or  contained  in the
Agreement  and  Plan  of  Reorganization  that I will  not  sell,  transfer,  or
otherwise dispose of any of the Shares unless Simmons has made public disclosure
of financial results reflecting 30 days' of post-Merger  combined  operations of
NBC  Corp.  and  Simmons  within  the  meaning  of  Section  201.01 of the SEC's
Codification  of Financial  Reporting  Policies.  Simmons has agreed to make the
required  public  disclosure  of  financial  results as set out above as soon as
feasible after the Merger is consummated.  In addition,  I hereby  represent and
warrant to Simmons that I have not made any sales of NBC Corp. or Simmons common
stock  during the 30-day  period  immediately  preceding  the date  hereof and I
further  agree not to engage in any such sales prior to the  Merger,  nor have I
pledged or will I pledge any  Simmons  or NBC Corp.  common  stock to secure any
obligation  during  such  period  (other  than the  continuation  of any  pledge
existing as of the date hereof).
    

         I represent and warrant to Simmons that:

   
         1. I have carefully read this letter and discussed its requirements and
other applicable limitations upon the sale, transfer or other disposition of the
Shares, to the extent I felt necessary, with my counsel or counsel for NBC Corp.
    

         2. I have been informed by Simmons that any  distribution  by me of the
Shares has not been registered under the Act and that the Shares must be held by
me  indefinitely  until (i) such  distribution of the Shares has been registered
under the Act, (ii) a sale of the Shares is made in  conformity  with the volume
and other limitations of Rule 145 promulgated by the SEC under the Act, or (iii)
some other  exemption  from  registration  is available with respect to any such
proposed sale, transfer or other disposition of the Shares.

         3. I have been informed by Simmons that it is required to file periodic
reports with the SEC and the NASDAQ and that  certain  sales of the Shares by me
may not be  required  to be  registered  under  the Act by  virtue  of Rule  145
promulgated  by the SEC under  the Act,  provided  that  such  sales are made in
accordance  with all of the terms and conditions of such Rules,  including among
other things the following:

     (a) The amount of Simmons  Common  Stock  sold by me  pursuant  to Rule 145
during any period of three months  cannot  exceed the greater of (i) one percent
of the total  outstanding  Simmons  Common  Stock or (ii) the  average  reported
weekly  trading  volume  on  NASDAQ  during  the four  week  period  immediately
preceding  receipt  of the order by the broker to execute  the  transaction.  In
computing the foregoing  quantity  limit it is necessary to count sales not only
by me but also by certain immediate family members and other related persons and
others with whom I may act in concert.

     (b) Sales must be made in brokers'  transactions as defined by the SEC Rule
144 (certain provisions of which are incorporated by reference into Rule 145).

     (c) No sales may be made under the Rule  unless  Simmons  has filed all SEC
reports required to be filed by Simmons.

         4. I  understand  that Simmons is under no  obligation  to register the
sale, transfer or other disposition of the Shares by me or on my behalf.

         5. I understand and agree that stop transfer instruction will be issued
with  respect  to the  Shares  and  there  will be  placed  on the  certificates
representing such Shares, or any certificate delivered in substitution therefor,
a legend stating in substance:

         "The shares  represented  by this  Certificate  have been issued to the
         registered  holder as a result of a transaction to which Rule 145 under
         the Securities Act of 1933, as amended,  ("the 1933 Act") applies.  The
         shares represented by this certificate may not be sold,  transferred or
         assigned,  and the issuer  shall not be  required to give effect to any
         attempted  sale,  transfer  or  assignment,  except  pursuant  to (i) a
         registration  statement  then in  effect  under  the 1933  Act,  (ii) a
         transaction  permitted  by Rule 145 as to which the issuer has received
         evidence of compliance  with the provisions of said Rule 145 reasonably
         satisfactory  to it or (iii) a  transaction  which,  in the  opinion of
         counsel  for  the  Affiliate  or  as  described  in  a  Ano-action"  or
         interpretive  letter  from the  staff of the  Securities  and  Exchange
         Commission,  in each case reasonably satisfactory in form and substance
         to the issuer, is exempt from the registration requirements of the 1933
         Act. The  restrictions of this paragraph shall become null and void and
         this  paragraph  shall have no effect on and after  [date 2 years after
         merger closing]."

         6. I have been  informed by Simmons that if I propose to sell to any of
these Shares pursuant to Rule 145, and if such sale would be permitted under the
terms of this letter, Simmons will, upon my written request,  supply me with the
following:

     (a) A statement as to whether  Simmons has complied with the  provisions of
Rule 145  regarding  filing of SEC reports as a condition to sales made pursuant
to that Rule;

     (b) A  confirmation  as to the  number of shares of  Simmons  Common  Stock
outstanding as shown by the most recent report or statement published by it; and

     (c) Simmons' taxpayer identification number and SEC file number.

   
         I have carefully read this letter and have had an adequate  opportunity
to  review  the  Merger  Agreement  and  understand  the  requirements  and  the
limitations imposed upon the distribution,  sale, transfer, or other disposition
of NBC Corp. common stock or Shares of Simmons.
    

                                                              Sincerely,