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                                                                    Exhibit 10.1

                             WESTOWER HOLDINGS LTD.
                          WESTOWER COMMUNICATIONS LTD.

                                CREDIT AGREEMENT

                                 Amendment No. 1

      This Agreement, dated as of August 21, 1998 (this "Agreement"), is among
Westower Corporation, a Washington corporation, its subsidiaries set forth on
the signature pages hereof, including Westower Holdings Ltd., a Wyoming
corporation (the "U.S. Borrower"), and Westower Communications Ltd., a British
Columbia, Canada corporation (the "Canadian Borrower") (together with the U.S.
Borrower, the "Borrowers") and BankBoston, N.A., as Agent for itself and the
other Lenders under the Credit Agreement (as defined below). The parties agree
as follows:

      1. Credit Agreement; Definitions. This Agreement amends the Credit
Agreement dated as of June 9, 1998 among the parties hereto and the Lenders (as
in effect prior to giving effect to this Agreement, the "Credit Agreement").
Terms defined in the Credit Agreement as amended hereby (the "Amended Credit
Agreement") and not otherwise defined herein are used with the meaning so
defined.

      2. Amendment of Credit Agreement. Effective upon the date hereof, the
Credit Agreement is amended as follows:

            2.1. Amendment of Section 1.158. The definition of "Tower Company"
      in Section 1.158 of the Credit Agreement is amended to read in its
      entirety as follows:

                  "1.158. 'Tower Company' means a corporation or any other
            entity engaged primarily in the same types of business as the
            Company and its Subsidiaries described in Section 6.2.1 of the
            Credit Agreement."

            2.2. Amendment of Section 6.4.4. Section 6.4.4 of the Credit
      Agreement is amended by replacing the words "15 Banking Days'" with the
      words "10 Banking Days'".

      3. Consent. Pursuant to Section 6.9.5(d) of the Credit Agreement, the
Lenders consent to the acquisition by the Company of (a) Standby Services, Inc.
pursuant to the Share Exchange Agreement, dated on or about August 31, 1998, (b)
CNG Communications, Inc. ("CNG"), pursuant to the Stock Purchase Agreement,
dated on or about August 31, 1998 and (c) American Television Relay, a business
unit of MCI Communications Corporation ("MCI"), pursuant to the
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Asset Purchase Agreement, dated on or about August 31, 1998, between CNG and MCI
(the "Proposed Acquisitions").

      4. Waiver. The Lenders hereby waive the requirement that the Company
deliver (a) the Tower Acquisition Report, as provided in Section 6.4.4 of the
Credit Agreement, 15 Business Days prior to the Proposed Acquisitions and (b)
certain computations, as provided in Section 6.9.5(a) of the Credit Agreement,
10 Banking Days prior to the Proposed Acquisitions; provided, that the Company
shall have delivered such report and computations to the Lenders prior to the
effectiveness of this Agreement.

      5. Representation and Warranty. In order to induce the Agent to enter into
this Agreement, each of the Borrowers and the Guarantors jointly and severally
represents and warrants that, after giving effect to this Agreement, no Default
exists.

      6. General. The Amended Credit Agreement and all of the Credit Documents
are each confirmed as being in full force and effect. This Agreement, the
Amended Credit Agreement and the other Credit Documents referred to herein or
therein constitute the entire understanding of the parties with respect to the
subject matter hereof and thereof and supersede all prior and current
understandings and agreements, whether written or oral. Each of this Agreement
and the Amended Credit Agreement is a Credit Document and may be executed in any
number of counterparts, which together shall constitute one instrument, and
shall bind and inure to the benefit of the parties and their respective
successors and assigns, including as such successors and assigns all holders of
any Credit Obligation. This Agreement shall be governed by and construed in
accordance with the laws (other than the conflict of law rules) of The
Commonwealth of Massachusetts.

               [The rest of this page is left intentionally blank]
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      Each of the undersigned has caused this Agreement to be executed and
delivered by its duly authorized officer as an agreement under seal as of the
date first written above.


                                    WESTOWER CORPORATION


                                    By /s/ Peter Lucas
                                       -----------------------------------
                                       Title: Chief Financial officer

                                    WESTOWER HOLDINGS LTD.
                                    WESTOWER COMMUNICATIONS LTD.
                                    MJA COMMUNICATIONS CORP.
                                    NATIONAL TOWER SERVICE LTD.
                                    RALPH'S RADIO INC.
                                    WESTERN TELECOM CONSTRUCTION LTD
                                    WESTOWER COMMUNICATIONS INC.
                                    WESTOWER LEASING CANADA INC.
                                    WTC HOLDINGS INC.
                                    WTC LEASING LTD. PARTNERSHIP
                                         By 582570 ALBERTA LTD., its general
                                    partner 3479021 CANADA INC.



                                    By  /s/ Peter Lucas
                                        -----------------------------------
                                        As an authorized officer of each of the
                                        foregoing corporations


                                    BANKBOSTON, N.A.,
                                       as Agent under the Credit Agreement


                                    By  /s/ Lenny Mason
                                        -----------------------------------
                                        Title: Vice President
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                                    The foregoing amendment is approved by the
                                    Lenders signing below:

                                    PARIBAS


                                    By /s/ Salo Aizendero
                                       -----------------------------------
                                       Title: Vice President

                                    By /s/ William B Schink
                                       -----------------------------------
                                       Title: Director


                                    PARIBAS BANK OF CANADA

                                    By /s/ James Goodall
                                       -----------------------------------
                                       Title: Managing Director

                                    By /s/ William R. Jeffrey
                                       -----------------------------------
                                       Title: Director


                                    FLEET NATIONAL BANK

                                    By Tanya M. Crossley
                                       -----------------------------------
                                       Title: Vice President


                                    U.S. BANK NATIONAL ASSOCIATION

                                    By Thomas G. Gunder
                                       -----------------------------------
                                       Title: Vice President


                                    UNION BANK OF CALIFORNIA, N.A.

                                    By Michael K. McShane
                                       -----------------------------------
                                    Title: Senior Vice President