1
                                                                   EXHIBIT 10.21

                                 AMENDMENT NO. 1
                        TO INTEREST CALCULATION AGREEMENT


                                                                    May 12, 2000


         WHEREAS, the parties hereto have previously entered into an Interest
Calculation Agreement, dated as of September 24, 1996 (the "Interest Calculation
Agreement"), between Banco Popular de Puerto Rico, a banking association
chartered under the laws of the Commonwealth of Puerto Rico (the "Bank"), and
The Chase Manhattan Bank, as interest calculation agent (the "Calculation
Agent") relating to the issue and sale by the Bank of its Bank Notes; and

         WHEREAS, the Bank and the Calculation Agent wish to amend the Interest
Calculation Agreement as provided herein;

         NOW, THEREFORE, the Bank and the Calculation Agent hereby agree to
amend the Interest Calculation Agreement as follows:

         1.       As of any time on or after the date of this amendment: (i)
each reference in the Interest Calculation Agreement to the "Distribution
Agreement" shall mean and be a reference to the Distribution Agreement, dated as
of September 24, 1996, among the Bank and Merrill Lynch & Co., Merrill Lynch,
Pierce, Fenner & Smith Incorporated, Bear, Stearns & Co. Inc. and CS First
Boston Corporation (now Credit Suisse First Boston Corporation) as amended as of
the date hereof; (ii) each reference in the Interest Calculation Agreement to
the "Issuing and Paying Agency Agreement" shall mean and be a reference to the
Issuing and Paying Agency Agreement, dated as of September 24, 1996, between the
Bank and The Chase Manhattan Bank, as Issuing and Paying Agent, as amended as of
the date hereof ; and (iii) each reference in the Interest Calculation Agreement
to "this Agreement", "hereunder", "hereof" or words of like import referring to
the Interest Calculation Agreement shall mean and be a reference to the Interest
Calculation Agreement as amended hereby.

         2.       As of any time on or after the date of this amendment, the
Interest Calculation Agreement, as amended hereby, is and shall continue to be
in full force and effect and as so amended is hereby ratified and confirmed and
is binding on the parties hereto.

         3.       This amendment may be executed by any one of the parties
hereto in any number of counterparts, each of which shall be an original, but
all of such counterparts shall together constitute one and the same instrument.



   2
         IN WITNESS WHEREOF, the parties hereto have caused this Amendment No. 1
to the Interest Calculation Agreement to be executed on their behalf as of the
day and year first above written.

                          BANCO POPULAR DE PUERTO RICO


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

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


                          THE CHASE MANHATTAN BANK,
                              as Calculation Agent

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


                                      -2-