Page 41
                                                         Exhibit 10(iii)A(13)(b)

                                 FIRST AMENDMENT
                                     TO THE
                        NATIONAL SERVICE INDUSTRIES, INC.
                  1992 NONEMPLOYEE DIRECTORS' STOCK OPTION PLAN




     THIS AMENDMENT made as of March 24, 1998, by National  Service  Industries,
Inc. ("NSI");



                              W I T N E S S E T H:



     WHEREAS, the 1992 Nonemployee Directors' Stock Option Plan (the "Plan") was
approved by the Board of  Directors of NSI on  September  16,  1992,  and by the
stockholders of NSI on January 6, 1993; and


     WHEREAS,  pursuant to the power of amendment  set forth in Section 9 of the
Plan and action of the Board of Directors of NSI on March 24, 1998;


     NOW, THEREFORE, the Plan is hereby amended as follows:


     1. Section 5.1 of the Plan is amended by deleting the "and" before  "(ii)",
by  replacing  "that the Plan  remains in effect  pursuant  to its  terms"  with
"through  the fiscal  year ending  August 31,  1998," and  inserting  "and (iii)
beginning with the fiscal year that commences  September 1, 1998, on the date of
the Annual  Meeting  each year that the Plan  remains in effect  pursuant to its
terms", so that Section 5.1 now reads in its entirety as follows:


          5.1 Grant. An Option shall be granted to each Nonemployee  Director on
          (i) the first  business day after the date of the first annual meeting
          of the stockholders of the Company  following  adoption of the Plan by
          the Board,  (ii) the third (3rd)  Wednesday  occurring in September of
          each year through the fiscal year ending  August 31,  1998,  and (iii)
          beginning  with the fiscal year that  commences  September 1, 1998, on
          the date of the  Annual  Meeting  each year that the Plan  remains  in
          effect  pursuant to its terms.  The number of Shares and the  purchase
          price  therefor of each Option  shall be as provided in this Section 5
          and such Options  shall be evidenced by an Agreement  containing  such
          other terms and  conditions  not  inconsistent  with the provisions of
          this Plan as determined by the Board.
 
Page 42
                                                         Exhibit 10(iii)A(13)(b)

     2.   Except as hereby  modified,  the Plan  shall  remain in full force and
          effect pursuant to its original terms.


          IN WITNESS WHEREOF, the parties hereto have executed this Amendment as
     of the day and year first written above.


ATTEST:                                        NATIONAL SERVICE INDUSTRIES, INC.





/s/ Carol Ellis Morgan               By:  /s/ James S. Balloun
Assistant Secretary                       James S. Balloun
                                          Chairman of  the Board, President  and
                                          Chief Executive Officer




(CORPORATE SEAL)