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                                                                  EXHIBIT 10.17

                                                                  EXECUTION COPY

                                LETTER AMENDMENT

                                             Dated as of October 4, 2002

To the banks, financial institutions
   and other institutional lenders
   (collectively, the "Lenders") parties
   to the Credit Agreement referred to
   below and to Citibank, N.A., as agent
   (the "Agent") for the Lenders

Ladies and Gentlemen:

                  We refer to the Credit Agreement dated as of June 21, 2002
(the "Credit Agreement") among the undersigned and you. Capitalized terms not
otherwise defined in this Letter Amendment have the same meanings as specified
in the Credit Agreement.

                  It is hereby agreed by you and us that the Credit Agreement
is, effective as of the date of this Letter Amendment, hereby amended as
follows:

                  (a)      Section 3.01(i) is amended in full to read as
        follows:

                  "(i)     The Borrower shall have received not less than
         $825,000,000 of proceeds (net of underwriting commissions) from the sum
         of (i) cash raised from the issuance of common shares in the Borrower's
         initial public offering; (ii) cash raised from the private placement of
         common shares to one or more strategic investor(s); and (iii) cash
         contributed by The St. Paul Companies, Inc."

                  (b)      Section 6.01(i) is amended in full to read as
         follows:

                  "(i)     (x) Any Insurance Subsidiary, after having obtained a
         financial strength rating from A.M. Best Company (a "Rating"), shall
         fail to maintain a Rating of A- or better, (y) any of Platinum
         Underwriters Reinsurance, Inc. and Platinum Underwriters Bermuda, Ltd.
         shall not have obtained a Rating within 30 days after the Effective
         Date or (z) Platinum Re (UK) Limited shall not have obtained a Rating
         within 30 days after obtaining a License from the Financial Services
         Authority in the United Kingdom".

                  This Letter Amendment shall become effective as of the date
first above written when, and only when, on or before October 4, 2002, the Agent
shall have received counterparts of this Letter Amendment executed by the
undersigned and all of the Lenders or, as to any of the Lenders, advice
satisfactory to the Agent that such Lender has executed this Letter Amendment.
This Letter Amendment is subject to the provisions of Section 8.01 of the Credit
Agreement.

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                  On and after the effectiveness of this Letter Amendment, each
reference in the Credit Agreement to "this Agreement", "hereunder", "hereof" or
words of like import referring to the Credit Agreement, and each reference in
the Notes to "the Credit Agreement", "thereunder", "thereof" or words of like
import referring to the Credit Agreement, shall mean and be a reference to the
Credit Agreement, as amended by this Letter Amendment.

                  The Credit Agreement and the Notes, as specifically amended by
this Letter Amendment, are and shall continue to be in full force and effect and
are hereby in all respects ratified and confirmed. The execution, delivery and
effectiveness of this Letter Amendment shall not, except as expressly provided
herein, operate as a waiver of any right, power or remedy of any Lender or the
Agent under the Credit Agreement, nor constitute a waiver of any provision of
the Credit Agreement.

                  If you agree to the terms and provisions hereof, please
evidence such agreement by executing and returning at least two counterparts of
this Letter Amendment to Susan L. Hobart, Shearman & sterling, 599 Lexington
Avenue, New York, New York 10022.

                  This Letter Amendment may be executed in any number of
counterparts and by different parties hereto in separate counterparts, each of
which when so executed shall be deemed to be an original and all of which taken
together shall constitute one and the same agreement. Delivery of an executed
counterpart of a signature page to this Letter Amendment by telecopier shall be
effective as delivery of a manually executed counterpart of this Letter
Amendment.

                  This Letter Amendment shall be governed by, and construed in
accordance with, the laws of the State of New York.

                                   Very truly yours,

                                   PLATINUM UNDERWRITERS HOLDINGS, LTD.

                                   By /s/ Jerome T. Fadden
                                      ---------------------------------------
                                      Title: President and Chief Executive
                                             Officer

Agreed as of the date first above written:

CITIBANK, N.A.,
         as Agent and as Lender

By /s/ M.A. Taylor
   ---------------------------
   Title: MICHAEL A. TAYLOR, VP
              Citibank N.A.
           388 Greenwich Street
               22nd Floor
              212-816-4033

JPMORGAN CHASE BANK

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JPMORGAN CHASE BANK

By /s/ Helen L. Newcomb
   ---------------------------
   Title: Vice President

BANK OF AMERICA, N.A.

By /s/ Leslie Reed
   ---------------------------
   Title: Vice President

FLEET NATIONAL BANK

By [SIGNATURE ILLEGIBLE]
   ---------------------------
   Title: Portfolio Manager

STATE STREET BANK AND TRUST COMPANY

By /s/ Edward M. Anderson
   --------------------------------------------
   Title: Vice President