FOURTH AMENDMENT AND WAIVER

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                                                                    EXHIBIT 10.5

                           FOURTH AMENDMENT AND WAIVER

     This Fourth Amendment and Waiver (this "Amendment") dated as of December

21, 2005, is by and among Willbros Group, Inc., a Republic of Panama corporation

(herein referred to as the "Company") and the Designated Subsidiaries; the

financial institutions parties hereto which are Banks under the Credit Agreement

(as defined below); and Calyon New York Branch (formerly known as Credit

Lyonnais New York Branch), as administrative agent for the Banks (in such

capacity, the "Agent"), and amends the Amended and Restated Credit Agreement

dated as of March 12, 2004, as previously amended by the First Amendment and

Waiver dated as of August 6, 2004, the Second Amendment and Waiver dated as of

July 19, 2005, and the Third Amendment and Waiver dated as of November 23, 2005

(the "Third Amendment"), among the Company, the Designated Subsidiaries from

time to time (WGI and such Designated Subsidiaries collectively, the "Obligors"

and individually, an "Obligor"); the several financial institutions from time to

time parties thereto as Banks, Calyon New York Branch (formerly known as Credit

Lyonnais New York Branch), as a Bank, as Issuing Bank (as defined herein), as

Agent, and as Lead Arranger and Book Runner; and CIBC, Inc., as Syndication

Agent (as previously amended and modified, the "Credit Agreement").

                             PRELIMINARY STATEMENTS

     Whereas, the Company intends to issue new Convertible Notes before December

31, 2005 on terms reasonably satisfactory to the Agent, in connection with which

Willbros U.S.A., Inc. will guarantee the Company's obligations under such

Convertible Notes pursuant to an unsecured guaranty;

     WHEREAS, after the issuance of such Convertible Notes, the Company will be

unable to comply with its covenant in Section 9.11(a) of the Credit Agreement to

maintain a ratio of Financial Indebtedness to Total Capitalization of no more

than 0.35 to 1.00, and its covenant in Section 9.13 of the Credit Agreement to

maintain a Fixed Charge Coverage Ratio of 3.00 to 1.00 for the fiscal quarter

ending June 30, 2006 and for each quarter thereafter, and has requested the

Banks to amend such covenants;

     WHEREAS, the Company failed to comply with its covenant in Section 9.11(c)

to not permit its ratio of Senior Secured Financial Indebtedness to Adjusted

EBITDA as of the fiscal quarter ending September 30, 2005 to exceed 1.00 to 1.00

(the "Senior Secured Financial Indebtedness Default") and has requested the

Banks to waive such default;

     WHEREAS, pursuant to the terms of the Third Amendment, the Banks previously

agreed to temporarily waive any Default or Event of Default that would occur

during the period through March 31, 2006 as a result of the Company's failure to

maintain a minimum cash balance of $15,000,000 (the "Prior Waiver");

     WHEREAS, the Banks have determined to limit the Prior Waiver to the period

up to the date upon which the Total Commitment is permanently reduced by the Net

Cash Proceeds from the Convertible Notes issuance and to reinstate from such

date the Company's obligation to maintain a minimum cash balance of $15,000,000

in accordance with Section 4.8 of the Credit Agreement; and

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     WHEREAS, the Banks and the Obligors have agreed to such amendments and

waiver, subject to the terms and conditions set forth in this Amendment;

                                    AGREEMENT

     NOW THEREFORE, in consideration of the premises and the mutual covenants

contained herein, and for other good and valuable consideration, the receipt and

sufficiency of which are hereby acknowledged, the parties hereto, intending to

be legally bound, hereby agree as follows. Capitalized terms used but not

otherwise defined herein shall have the meanings assigned such terms in the

Credit Agreement.

     Section 1. Waiver. The Banks hereby agree to waive the Senior Secured

Financial Indebtedness Default for the quarter ending September 30, 2005. The

express waiver set forth in this section is the only waiver provided by the

Agent and the Banks pursuant to this Amendment, and all other rights and

remedies of the Agent and the Banks under the Credit Agreement remain unchanged.

     Section 2. Amendments of Credit Agreement. Subject to the satisfaction of

the conditions described in Section 4 hereof, the Credit Agreement is hereby

amended as follows:

          (a) The defined term "Change of Control" in Section 1.1 of the Credit

     Agreement is hereby amended as of the Amendment Effective Date by adding

     the following clause to the end thereof: "or (c) the occurrence of any

     Fundamental Change as such term is defined in each indenture governing

     Convertible Notes".

          (b) Section 9.11(a) of the Credit Agreement is hereby amended as of

     September 30, 2005 by restating such subsection in its entirety as follows:

               (a) The Company shall not permit the ratio of (i) the Financial

          Indebtedness of the Company minus 100% of unrestricted cash and Cash

          Equivalents of the Company on the Company's balance sheet (excluding

          any such cash and Cash Equivalents in the Cash Collateral Account) to

          (ii) Total Capitalization minus 100% of unrestricted cash and Cash

          Equivalents of the Company on the Company's balance sheet (excluding

          any such cash and Cash Equivalents in the Cash Collateral Account), at

          the end of any fiscal quarter to exceed 0.50 to 1.00.

          (c) Section 9.13 of the Credit Agreement is hereby amended as of the

     Amendment Effective Date by restating such section in its entirety as

     follows:

          Fixed Charge Coverage Ratio. The Company shall not permit its Fixed

           Charge Coverage Ratio, calculated at the end of each fiscal quarter on

          and after June 30, 2006 for the four fiscal quarter period then ended,

          to be less than 2.50 to 1.00.

     Section 3. Additional Agreements. The Banks and the Obligors agree that the

following agreements shall apply as if fully incorporated into the terms of the

Credit Agreement:

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          (a) No later than December 28, 2005, the Company shall provide to the

     Agent evidence satisfactory to the Agent that the Company has received Net

     Cash Proceeds of at least $30,000,000 from the sale of new Convertible

     Notes, and failure to provide such satisfactory evidence by such date shall

     automatically be deemed an Event of Default under the Credit Agreement, and

     the Agent may exercise, or shall exercise at the request of the Required

     Banks, any remedies provided under the terms of the Credit Agreement.

          (b) Notwithstanding anything to the contrary in the Third Amendment,

     from and after the date upon which the Company receives Net Cash Proceeds

     from the sale of new Convertible Notes, the obligation of the Company under

     Section 4.8 of the Credit Agreement to maintain a minimum cash balance of

     $15,000,000 shall be in full force and effect.

          (c) The Obligors shall provide within thirty (30) days of the date

     hereof, the following corporate documents:

               (i) (A) copies of the certificate or articles of incorporation or

          other equivalent organizational documents, including all amendments

          thereto, of each Obligor, certified as of a recent date by the

          Secretary of State of the state of its organization or the foreign

           equivalent thereof in each jurisdictio