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                                                         Exhibit 10(iii)A(28)(a)




B.A. Hattox
August 26, 1996
                                                     August 26, 1996


Mr. Brock A. Hattox
19206 Hanston Court
Houston, Texas   77094


Dear Brock:


     This letter will confirm the terms of your  employment by National  Service
Industries,  Inc. ("NSI") and NSI Services,  L.P.,  effective  September 9, 1996
(the "Effective  Date"). We are enthusiastic about your decision to join NSI and
look forward to working with you to enhance NSI's future growth.

     The terms of your employment,  which are subject, of course, to approval by
our Executive Resource and Nominating Committee and the Board of Directors, will
be as follows:

     1. Duties - You will be nominated for election as Executive  Vice President
and  Chief  Financial  Officer  at the  meeting  of our  Board of  Directors  on
September  18, 1996.  You will also serve in the same capacity for NSI Services,
L.P.  (the  "Partnership").  You will  assume the  duties  and  responsibilities
commensurate  with those  positions,  which  will  include  service to NSI,  the
Partnership,  and other  subsidiaries  and  partnerships  of NSI and may receive
compensation,  benefits,  and other  amounts from such  entities,  the aggregate
amount of which  will  equal the sums and  benefits  specified  herein.  Between
September 9 and  September  18, 1996,  you will perform  substantially  the same
duties as  outlined  above as  assistant  to the  Chairman  of the Board for the
salary set forth in paragraph 2 below. You will devote substantially all of your
working time and attention to the business and affairs of NSI.

     2. Base Salary - Your base  salary for the fiscal  year  ending  August 31,
1997 ("fiscal 1997"), will be at the annual rate of Three Hundred Fifty Thousand
Dollars ($350,000).  Thereafter,  your base salary will be subject to review for
increases at such time as NSI conducts  salary  reviews for  executive  officers
generally.

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Exhibit 10(iii)A(28)(a)

     3.  Annual  Incentive  Compensation  - You  will  participate  in  the  NSI
Management  Compensation and Incentive Plan (the "AIP") for fiscal 1997 and will
receive a bonus under the AIP of at least One  Hundred  Fifty  Thousand  Dollars
($150,000) for fiscal 1997.

     4. Stock  Options - You will receive a grant of employee  stock options for
twenty thousand (20,000) shares of stock under our current  long-term  incentive
plan upon your arrival at NSI. In addition,  you will receive a grant of options
for at least twenty thousand (20,000) shares at the September 1996 board meeting
under either our current long-term  incentive plan or a new plan to be presented
to the Board at the meeting.

     5. Retirement  Plans - Upon satisfying the  eligibility  requirements,  you
will be eligible to participate in NSI's  tax-qualified  retirement  plans,  NSI
Pension  Plan C, and the NSI 401(k)  Plan for  Corporate  Office  Employees.  In
addition,  on  September  18,  1996,  you  will  become  a  participant  in  the
Supplemental  Retirement Plan for Executives of NSI (the "SERP").  Your benefits
under  the SERP will be  determined  in the same  manner as for other  executive
officers  of NSI  participating  in the plan  (other  than the  Chief  Executive
Officer),  except that you will be credited with service under the SERP for each
year of actual  service.  You will  become  vested in your  SERP  benefit  after
completing  five (5) years of employment with NSI and will be eligible for early
retirement at age sixty (60).

     6.  Medical,  Life  Insurance,  and Other  Employee  Benefits - You will be
covered by, or eligible to participate in, the medical,  dental, life insurance,
disability,  deferred  compensation,  and other benefit programs  generally made
available by NSI to its executive  officers and their families,  including a car
allowance of Four Hundred Dollars ($400) per month.

     7. Relocation Expenses - We will pay the following relocation expenses:

        (a)  your expenses for moving your household effects to Atlanta;

        (b)  three (3) months rent for an apartment and storage of your personal
             effects in Atlanta, pending your move into your new home; and


                                                                         Page 55
                                                         Exhibit 10(iii)A(28)(a)

        (c)  brokerage and closing costs you incur in connection with the sale
             of your home in Houston and the purchase of a home in Atlanta.

     8. Severance Payment/Change in Control - Except in the event of termination
in  connection  with a Change in  Control of NSI (as  defined  in the  Severance
Protection Agreement that will cover you), you will be entitled to the following
severance payment:

     *    If your employment is terminated on or before August 31, 1999,  except
          for voluntary  termination,  termination  upon death or Disability (as
          defined  below),  or termination by NSI for Cause (as defined  below),
          you will receive (a) a severance  payment (payable in twenty-four (24)
          semi-monthly  installments) equal to your then current salary plus any
          annual incentive received for the preceding fiscal year, and (b) a pro
          rata bonus for the fiscal year  during  which you are  terminated.  In
          addition to the foregoing,  any employee  options you hold at the date
          of  termination  will be  vested  and you will be given  two (2) years
          following termination to exercise them.

     *    For purposes of entitlement to a severance benefit, "Cause" shall mean
          any act(s) on your part that  constitutes  fraud,  a felony  involving
          dishonesty,  a breach  of  fiduciary  duty,  or gross  malfeasance  or
          habitual neglect of your duties for NSI, and "Disability" shall mean a
          physical  or  mental   infirmity   which   impairs   your  ability  to
          substantially  perform your duties as Chief  Financial  Officer of NSI
          for a period of one hundred  eighty (180)  consecutive  days.  The NSI
          Board,  based upon the  information  provided to it,  shall  determine
          whether an act  constituting  Cause has  occurred and whether you have
          suffered a Disability.  In the case of termination for Cause,  (i) you
          will be given  written  notice of the  actions  constituting  Cause at
          least fifteen (15) days prior to any meeting of the Board of Directors
          of NSI at which your termination is to be considered; (ii) you will be
          given  the  opportunity  to be  heard by the  Board;  and  (iii)  your
          termination  for Cause must be evidenced by a resolution  adopted by a
          majority of the Board.

With respect to Change in Control situations, you will be covered by a Severance
Protection  Agreement with the same  provisions as are applicable to NSI's other

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Exhibit 10(iii)A(28)(a)


executive officers. In the event of your termination in connection with a Change
in  Control  that  entitles  you to  benefits  under  the  Severance  Protection
Agreement,  you will receive the greater of the  payments and benefits  provided
under  the  Severance  Protection  Agreement  (after  consideration  of any  tax
penalties) or the severance payments described above.

     The base salary, annual incentive,  option grants,  nonqualified retirement
benefits,  and any  severance  payments  will be  structured  to ensure  the tax
deductibility  to NSI of the payments and  benefits  under the Internal  Revenue
Code  of  1986,  including  Code  Section  162(m).  We  can  provide  additional
information on these issues if you so desire.

     We will prepare a SERP  provision  and  Severance  Protection  Agreement to
evidence the arrangements set forth in this letter.

     Again,  we are  delighted you are joining NSI and we look forward to a long
and mutually  satisfactory  relationship.  This letter  outlines your employment
relationship with NSI; if you agree with the employment terms as outlined above,
please sign and date both copies of this letter agreement and return one copy to
me at your earliest convenience.

                                          Sincerely,


                                          /s/ James S. Balloun 
                                          James S. Balloun

ACCEPTED AND AGREED TO THIS

_____ DAY OF _____________, 1996



/s/ Brock A. Hattox
Brock A. Hattox