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                                                            EXHIBIT 10(iii)A(20)



                           NATIONAL SERVICE INDUSTRIES

                                    AMENDMENT
                                       TO
                             STOCK OPTION AGREEMENTS

         THIS AMENDMENT made and entered into as of the 24th day of July,
2001, by and between National Service Industries, Inc., a Delaware corporation
(the "Company") and Brock A. Hattox ("Optionee").

         WHEREAS, the Company has previously adopted the National Service
Industries, Inc. Long-Term Incentive Program ("LTIP") and the National Service
Industries, Inc. Long-Term Achievement Incentive Plan ("LTAIP") to provide
additional incentives to certain officers and key employees of the Company and
its Subsidiaries; and

         WHEREAS, the Optionee has been granted the Incentive Stock Options
(ISOs) and Nonqualified Stock Options (NQSOs) listed on Exhibits A, B, and C
attached hereto (collectively the "Options") under the LTIP and the LTAIP; and

         WHEREAS, the terms and conditions of the grants of the Options are
reflected in Stock Option Agreements (the "Stock Option Agreements") between the
Company and Optionee; and

         WHEREAS, the Company and the Optionee desire to amend the Stock Option
Agreements for the Options in the manner hereinafter provided;

         NOW, THEREFORE, the parties agree as follows:

                                       1.

         Each of the Stock Option Agreements for the Options listed on Exhibit A
attached hereto is hereby amended to renumber the existing Section 6.1 as
Section 6.1(a) and to insert the following as a new subsection 6.1(b):

                  "(b) Termination After Attaining Age 55. If the Optionee
         terminates employment (other than as a result of death or Disability)
         after attaining age 55 but prior to age 65, unless the Committee
         determines otherwise at the time of such termination, the Option shall
         continue to vest in accordance with the original schedule (just as if
         the Optionee had remained employed) and shall remain exercisable until
         five (5) years after the date of termination (but not beyond the
         Exercise Term). In the event of the Optionee's death after such
         termination, the Option shall continue to be exercisable in accordance
         with this subsection (b) as if the Optionee had lived and the Option
         shall be exercisable by the persons described in (a) above."


<PAGE>

                                       2.

         The Stock Option Agreement for the Option listed on Exhibit B attached
hereto is hereby amended to insert the following as a new subsection 6.2(d):

                  "(d)  Termination After Attaining Age 55. If the Optionee
         terminates employment (other than as a result of death or Disability)
         after attaining age 55 but prior to age 65, unless the Committee
         determines otherwise at the time of such termination, the Option shall
         continue to vest in accordance with the original schedule (just as if
         the Optionee had remained employed) and shall remain exercisable until
         five (5) years after the date of termination (but not beyond the
         Exercise Term). In the event of the Optionee's death after such
         termination, the Option shall continue to be exercisable in accordance
         with this subsection (d) as if the Optionee had lived and the Option
         shall be exercisable by the persons described in (a) above."

                                       3.

         Each of the Stock Option Agreements for the Options listed on Exhibit C
attached hereto is hereby amended to delete the existing Section 6.2 in its
entirety and to substitute the following in lieu thereof:

                  "6.2     Termination of Employment Due to Specified Reasons.

                           If the Optionee's termination of employment is due to
death, Disability, Retirement (termination on or after age 65), termination by
the Company other than for cause, termination after attaining age 55, or
voluntary termination, the following shall apply:

                  (a)      Termination Due To Death. In the event the Optionee
                           dies while actively employed, the Option shall remain
                           exercisable until seven (7) years after the date of
                           grant or five (5) years after the date of
                           termination, whichever is later (but in any event not
                           beyond the Exercise Term), by (A) a Permitted
                           Transferee (as defined in Section 8 below), if any,
                           or such person(s) that have acquired the Optionee's
                           rights under such Option by will or by the laws of
                           descent and distribution, or (B) if no such person
                           described in (A) exists, the Optionee's estate or
                           representative of the Optionee's estate.

                  (b)      Termination by Disability. In the event the
                           employment of the Optionee is terminated by reason of
                           Disability, the Option shall remain exercisable until
                           seven (7) years after the date of grant or five (5)
                           years after the date the Committee determines the
                           Optionee terminated for Disability, whichever is
                           later (but in any event not beyond the Exercise
                           Term). In the event of the Optionee's death after
                           such termination, the Option shall continue to be
                           exercisable in accordance with this subsection (b) as
                           if the


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                           Optionee had lived and the Options shall be
                           exercisable by the persons described in (a) above.

                  (c)      Termination by Retirement or by the Company Without
                           Cause. In the event the employment of the Optionee is
                           terminated by reason of Retirement (at or after age
                           65) or by the Company for any reason other than for
                           cause, the Option shall remain exercisable until
                           seven (7) years after the date of grant or five (5)
                           years after the date of termination, whichever is
                           later (but in any event not beyond the Exercise
                           Term). In the event of the Optionee's death after
                           such Retirement or termination, the Option shall
                           continue to be exercisable in accordance with this
                           subsection (c) as if the Optionee had lived and the
                           Options shall be exercisable by the persons described
                           in (a) above.

                  (d)      Termination After Attaining Age 55. In the event the
                           Optionee terminates employment (other than as a
                           result of death or Disability) after attaining age 55
                           but prior to age 65, unless the Committee determines
                           otherwise at the time of such termination, the Option
                           shall continue to vest in accordance with the
                           original schedule (just as if the Optionee had
                           remained employed) and shall remain exercisable until
                           five (5) years after the date of termination (but in
                           any event not beyond the Exercise Term). In the event
                           of the Optionee's death after such termination, the
                           Option shall continue to be exercisable in accordance
                           with this subsection (d) as if the Optionee had lived
                           and the Options shall be exercisable by the persons
                           described in (a) above.

                  (e)      Voluntary Termination. In the event Optionee
                           voluntarily terminates employment, the Options shall
                           remain exercisable until ninety (90) days after the
                           date of termination (but not beyond the Exercise
                           Term)."

                                       4.

         This Amendment shall be effective as of July 24, 2001. Except as hereby
modified, the Stock Option Agreements shall remain in full force and effect.

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


                                       NATIONAL SERVICE INDUSTRIES, INC.



                                       By:
                                          --------------------------------------



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<PAGE>



                                       -----------------------------------------
                                                     BROCK A. HATTOX


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<PAGE>

                                    Exhibit A

<TABLE>
<CAPTION>
----------------------------------------------------------------------------------------------------------------------
                      Expiration
Grant Date            Date               Plan ID             Grant Type         # Options           Option Price
----------------------------------------------------------------------------------------------------------------------
<S>                   <C>                <C>                 <C>                <C>                 <C>
9/9/1996              9/9/2006           LTIP                ISO                10,524              $38.00
----------------------------------------------------------------------------------------------------------------------
9/9/1996              9/9/2006           LTIP                NQSO               9,476               $38.00
----------------------------------------------------------------------------------------------------------------------
</TABLE>


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<PAGE>

                                    Exhibit B

<TABLE>
<CAPTION>
----------------------------------------------------------------------------------------------------------------------
                      Expiration
Grant Date            Date               Plan ID             Grant Type         # Options           Option Price
----------------------------------------------------------------------------------------------------------------------
<S>                   <C>                <C>                 <C>                <C>                 <C>
9/17/1996             9/17/2006          LTIP                NQSO               20,000              $38.00
----------------------------------------------------------------------------------------------------------------------
</TABLE>


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<PAGE>

                                    Exhibit C
<TABLE>
<CAPTION>
----------------------------------------------------------------------------------------------------------------------
                      Expiration
Grant Date            Date               Plan ID             Grant Type         # Options           Option Price
----------------------------------------------------------------------------------------------------------------------
<S>                   <C>                <C>                 <C>                <C>                 <C>
1/5/2000              1/5/2010           LTAIP               NQSO               65,001              $27.6875
----------------------------------------------------------------------------------------------------------------------
10/4/2000             10/4/2010          LTAIP               NQSO               57,312              $19.4375
----------------------------------------------------------------------------------------------------------------------
</TABLE>


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