EXHIBIT 10.7



             AMENDMENT NUMBER THREE TO REVOLVING CREDIT AGREEMENT


      This  AMENDMENT   NUMBER  THREE  TO  REVOLVING   CREDIT   AGREEMENT  (this
"Amendment"),  dated  as of July  21,  2003,  is  entered  into  among  NATIONAL
TECHNICAL  SYSTEMS,  INC., a California  corporation  ("Parent"),  NTS TECHNICAL
SYSTEMS,  a California  corporation,  dba National  Technical  Systems  ("NTS"),
XXCAL,  INC., a California  corporation  ("XXCAL"),  APPROVED  ENGINEERING  TEST
LABORATORIES,  INC., a California corporation ("AETL"), ETCR, INC., a California
corporation ("ETCR"),  ACTON ENVIRONMENTAL TESTING CORPORATION,  a Massachusetts
corporation  ("Acton"),  and one or more  Subsidiaries  of Parent,  whether  now
existing or hereafter  acquired or formed,  which become party to the  Agreement
(as  defined  below) by  executing  an  Addendum in the form of Exhibit 1 of the
Agreement  (NTS,  XXCAL,  AETL,  ETCR,  Acton and such  other  Subsidiaries  are
sometimes  individually  referred  to  herein  as a  "Subsidiary  Borrower"  and
collectively  referred  to  herein as  "Subsidiary  Borrowers",  and  Subsidiary
Borrowers  and  Parent  are  sometimes  individually  referred  to  herein  as a
"Borrower" and collectively  referred to herein as  "Borrowers"),  the financial
institutions  from time to time parties hereto as Lenders,  whether by execution
hereof or an Assignment and Acceptance in accordance with Section 11.5(c) of the
Agreement,  and  Comerica  Bank -  California,  in its  capacity as  contractual
representative for itself and the other Lenders ("Agent"), with reference to the
following facts:

      A.  Borrowers,  Agent and Lenders  previously  entered  into that  certain
Revolving  Credit  Agreement,  dated as of November 21, 2001, as amended by that
certain Amendment Number One to Revolving Credit Agreement, dated as of July 17,
2002 and that certain Amendment Number Two to Revolving Credit Agreement,  dated
as of November 25, 2002 (as amended, the "Agreement");

      B.  Borrowers,  Agent  and  Lenders  desire  to  amend  the  Agreement  in
accordance with the terms of this Amendment.

      NOW,  THEREFORE,  in  consideration  of the foregoing,  the parties hereto
hereby agree as follows:

      8. Defined  Terms.  All initially  capitalized  terms used but not defined
herein shall have the meanings assigned to such terms in the Agreement.

      Amendment to Section 1.1. The  definition  of  "Revolving  Loans  Maturity
Date"  set forth in  Section  1.1 of the  Agreement  is  hereby  amended  in its
entirety as follows:

            "`Revolving Loans Maturity Date' means August 1, 2005."

      9. Amendment to Section 7.15(a).  Section 7.15(a) is hereby amended in its
entirety as follows:

            "(a) Consolidated  Effective Tangible Net Worth,  measured as of the
end of each  fiscal  quarter,  at any time to be less than  $24,900,000  plus an
amount  equal to  twenty-five  percent  (25%) of the  Consolidated  Adjusted Net
Income for each fiscal year,  commencing with the fiscal year ending January 31,
2004 (but in no event  less than zero with  respect to any  fiscal  year)."

      10. Conditions Precedent to Effectiveness of Amendment.  The effectiveness
of this Amendment is subject to and contingent  upon the fulfillment of each and
every one of the following conditions:

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            Agent  shall  have  received  this   Amendment,   duly  executed  by
Borrowers, Lenders and Agent;

            No Event  of  Default,  Unmatured  Event of  Default  or  Material
Adverse Effect shall have occurred; and

            All of the  representations  and warranties set forth herein, in the
Loan Documents and in the Agreement shall be true,  complete and accurate in all
respects as of the date hereof (except for  representations and warranties which
are expressly stated to be true and correct as of the Closing Date).

      11.  Representations and Warranties.  In order to induce Agent and Lenders
to enter into this Amendment,  each Borrower  hereby  represents and warrants to
Agent and Lenders that:

            No Event of Default or Unmatured Event of Default is continuing;

            All of the representations and warranties set forth in the Agreement
and the Loan Documents are true,  complete and accurate in all respects  (except
for  representations  and warranties  which are expressly  stated to be true and
correct as of the Closing Date); and

            This  Amendment  has been duly  executed and delivered by Borrowers,
and after giving effect to this Amendment,  the Agreement and the Loan Documents
continue to constitute the legal,  valid and binding  agreements and obligations
of  Borrowers,   enforceable   in  accordance   with  their  terms,   except  as
enforceability  may be limited by bankruptcy,  insolvency,  and similar laws and
equitable principles affecting the enforcement of creditors' rights generally.

      12. Counterparts;  Telefacsimile Execution. This Amendment may be executed
in any number of counterparts and by different parties on separate counterparts,
each of which,  when executed and delivered,  shall be deemed to be an original,
and all of which,  when taken  together,  shall  constitute but one and the same
Amendment.   Delivery  of  an  executed   counterpart   of  this   Amendment  by
telefacsimile  shall be equally as effective as delivery of a manually  executed
counterpart of this Amendment.  Any party delivering an executed  counterpart of
this  Amendment  by  telefacsimile   also  shall  deliver  a  manually  executed
counterpart  of this  Amendment  but the failure to deliver a manually  executed
counterpart shall not affect the validity, enforceability, and binding effect of
this Amendment.

      13.  Integration.  The Agreement as amended by this Amendment  constitutes
the entire agreement and  understanding  between the parties hereto with respect
to the subject  matter  hereof and  thereof,  and  supersedes  any and all prior
agreements and understandings,  oral or written,  relating to the subject matter
hereof and thereof.

      14.  Reaffirmation  of the Agreement.  The Agreement as amended hereby and
the other Loan Documents remain in full force and effect.



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      IN WITNESS  WHEREOF,  the parties  hereto have duly executed and delivered
this Amendment as of the date first hereinabove written.

                        NATIONAL TECHNICAL SYSTEMS, INC.


                        By  /s/ Lloyd Blonder
                            ----------------------------------------------------
                            Lloyd Blonder, Senior Vice President, Chief
                            Financial Officer, Treasurer and Assistant Secretary


                        NTS TECHNICAL SYSTEMS dba
                        NATIONAL TECHNICAL SYSTEMS


                        By  /s/ Lloyd Blonder
                            ----------------------------------------------------
                            Lloyd Blonder, Senior Vice President, Chief
                            Financial Officer, Treasurer and Assistant Secretary



                        XXCAL, INC.


                        By   /s/ Lloyd Blonder
                            ----------------------------------------------------
                            Lloyd Blonder, Vice President, Treasurer and
                            Assistant Secretary


                        APPROVED ENGINEERING TEST
                        LABORATORIES, INC.


                        By  /s/ Lloyd Blonder
                            ----------------------------------------------------
                            Lloyd Blonder, Vice President, Treasurer and
                            Assistant Secretary


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                        ETCR, INC.


                        By  /s/ Lloyd Blonder
                            ----------------------------------------------------
                            Lloyd Blonder, Vice President,
                            Treasurer and Assistant Secretary


                        ACTON ENVIRONMENTAL TESTING CORPORATION


                        By   /s/ Lloyd Blonder
                            ----------------------------------------------------
                            Lloyd Blonder, Vice President,
                            Treasurer and Assistant Secretary



                        COMERICA BANK-CALIFORNIA, in its capacities as
                        Agent, Issuing Lender and a Lender


                        By  /s/ Jason D. Brown
                            ----------------------------------------------------
                            Jason D. Brown, Vice President


                        FIRST BANK & TRUST, in its capacity as aLender


                        By  /s/ Nabil B. Khoury
                            ----------------------------------------------------
                            Name  Nabil B. Khoury
                                  ----------------------------------------------
                            Title Vice President Commercial Banking
                                  ----------------------------------------------


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