<PAGE>

                                                                    EXHIBIT 10.5

                      FOURTH AMENDMENT TO CREDIT AGREEMENT
                      ------------------------------------

          FOURTH AMENDMENT TO CREDIT AGREEMENT (this "Amendment"), dated as of
June 29, 2001, among U.S.I. HOLDINGS CORPORATION, a Delaware corporation (the
"Borrower"), the various lenders from time to time party to the Credit Agreement
referred to below (the "Lenders"), CREDIT LYONNAIS CAYMAN ISLAND BRANCH, as
Administrative Agent (the "Administrative Agent") and THE CHASE MANHATTAN BANK,
as Syndication Agent (the "Syndication Agent"). All capitalized terms used
herein and not otherwise defined shall have the respective meanings assigned to
such terms in the Credit Agreement.

                              W I T N E S S E T H:
                              - - - - - - - - - -

          WHEREAS, the Borrower, the Lenders, the Administrative Agent and the
Syndication Agent are parties to a Credit Agreement, dated as of September 17,
1999 (as amended, modified or supplemented to the date hereof, the "Credit
Agreement");

          WHEREAS, the Borrower has requested that the Lenders agree to amend
certain provisions of the Credit Agreement as herein provided; and

          WHEREAS, the Lenders have agreed to the amendments to the Credit
Agreement as herein provided, subject to the terms and conditions set forth
herein;

          NOW, THEREFORE, the parties hereto agree as follows:

          1. Section 7.1 of the Credit Agreement is hereby amended by:

          (i) deleting the table appearing in subsection (a) in its entirety and
inserting in lieu thereof the following new table:

Date                            Ratio
----                            -----
March 31, 2000                  4.85
June 30, 2000                   4.75
September 30, 2000              4.50
December 31, 2000               4.25
March 31, 2001                  3.75
June 30, 2001                   4.00
September 30, 2001              4.00
Decmber 31, 2001                3.50
March 31, 2002                  3.25
June 30, 2002 and the last
day of each fiscal quarter
thereafter                      3.25

<PAGE>

          (ii) deleting the table appearing in subsection (d) in its entirety
and inserting in lieu thereof the following new table:

Fiscal Quarter             Amount
--------------             ------
March 31, 2000          $190,000,000
June 30, 2000           $190,000,000
September 30, 2000      $190,000,000
December 31, 2000       $190,000,000
March 31, 2001          $185,000,000
June 30, 2001           $175,000,000
September 30, 2001      $170,000,000
December 31, 2001       $180,000,000
March 31, 2002          $225,000,000
June 30, 2002           $225,000,000
September 30, 2002      $225,000,000
December 31, 2002       $225,000,000
March 31, 2003          $250,000,000
June 30, 2003           $250,000,000
September 30, 2003      $250,000,000
December 31, 2003       $250,000,000
March 31, 2004          $250,000,000
June 30, 2004           $250,000,000
September 30, 2004      $250,000,000

          (iii) deleting the phrase "3.75% of the Borrower's consolidated total
revenues (determined in accordance with GAAP) for its 2000 fiscal year" from
subsection (e)(iii) and inserting "$16 million" in lieu thereof.

          2. The Borrower hereby represents and warrants that (x) all
representations and warranties contained in Section 4 of the Credit Agreement
are true and correct in all material respects on and as of the Fourth Amendment
Effective Date (as defined below) after giving effect to this Amendment (unless
such representations and warranties relate to a specific earlier date, in which
case such representations and warranties shall be true and correct as of such
earlier date) and (y) there exists no Default or Event of Default on the Fourth
Amendment Effective Date, after giving effect to this Amendment.

          3. This Amendment is limited as specified and shall not constitute a
modification, acceptance or waiver of any provision of the Credit Agreement or
any other Loan Document except as expressly set forth herein.

          4. This Amendment may be executed in any number of counterparts and by
the different parties hereto on separate counterparts, each of which
counterparts when executed and delivered shall be an original, but all of which
shall together constitute one and the same instrument. A complete set of
counterparts shall be lodged with the Borrower and the Administrative Agent.

                                       2

<PAGE>

          5 THIS AMENDMENT AND THE RIGHTS AND OBLIGATIONS OF THE PARTIES
HEREUNDER SHALL BE CONSTRUED IN ACCORDANCE WITH AND GOVERNED BY THE LAW OF THE
STATE OF NEW YORK

          6. This Amendment shall become effective as of the date hereof on the
date (the "Fourth Amendment Effective Date") when each of the Borrower and the
Required Lenders shall have signed a counterpart hereof (whether the same or
different counterparts) and shall have delivered (including by way of facsimile
transmission) the same to the Administrative Agent at its notice office, shall
have been signed by the parties thereto.

          7. From and after the Fourth Amendment Effective Date, all references
in the Credit Agreement and each of the Loan Documents to the Credit Agreement
shall be deemed to be references to the Credit Agreement after giving effect to
this Amendment.

                                     * * *

                                        3

<PAGE>

          IN WITNESS WHEREOF, the parties hereto have caused a counterpart of
this Amendment to be duly executed and delivered as of the date first above
written.

                                             U.S.I. HOLDINGS CORPORATION


                                             By /s/ Bernard H. Mizel
                                               ---------------------------------
                                                Name:  Bernard H. Mizel
                                                Title: Chairman & CEO


                                             CREDIT LYONNAIS CAYMAN ISLAND
                                                BRANCH


                                             By /s/ W. Michael George
                                               ---------------------------------
                                                Name: W. Michael George
                                                Title: Authorized Signature


                                             THE CHASE MANHATTAN BANK


                                             By /s/ Elisabeth H. Schwobe
                                               ---------------------------------
                                                Name:  Elisabeth H. Schwobe
                                                Title: Managing Director


                                             FIRSTAR BANK, N.A.


                                             By
                                               ---------------------------------
                                                Name:
                                                Title:

<PAGE>

                                             LASALLE BANK NATIONAL
                                               ASSOCIATION F/K/A LASALLE
                                               NATIONAL BANK


                                             By /s/ George L. Kumis
                                               ---------------------------------
                                               Name: George L. Kumis
                                               Title: Senior Vice President


                                             PILGRIM PRIME RATE TRUST


                                             By: ING Pilgrim Investments
                                                 as its investment manager


                                             By /s/ Michel Prince
                                               ---------------------------------
                                               Name:  Michel Prince, CFA
                                               Title: Vice President


                                             PILGRIM AMERICA HIGH INCOME
                                               INVESTMENTS, LTD.


                                             By: ING Pilgrim Investments, Inc.
                                                 as its investment manager


                                             By /s/ Michel Prince
                                               ---------------------------------
                                               Name:  Michel Prince, CFA
                                               Title: Vice President