<PAGE>

                                                                   EXHIBIT 10.44

                      FOURTH AMENDMENT TO CREDIT AGREEMENT

        This FOURTH AMENDMENT TO CREDIT AGREEMENT dated as of December 30, 2001
(this "Amendment"), among RUBIO'S RESTAURANTS, INC AND RUBIO'S RESTAURANTS OF
NEVADA, INC. (collectively the "Borrower") and FLEET NATIONAL BANK formerly
known as BANKBOSTON, N.A., (the "Bank").

        WHEREAS, pursuant to the Credit Agreement (as defined below), the Bank
has agreed to make Revolving Credit Loans to the Borrower as provided in the
Credit Agreement (as defined below);

        WHEREAS, the Borrower and the Bank wish to revise certain provisions of
the Credit Agreement as provided below amending certain covenants and making
certain other changes to the Credit Agreement.

        NOW, THEREFORE, in consideration of the foregoing and the agreements
contained herein, the parties hereby agree as follows:

1)      REFERENCE TO CREDIT AGREEMENT.

        Reference is made to the Revolving Credit and Term Loan Agreement dated
as of May 13, 1998 (as the same may be amended and restated from time to time,
the "Credit Agreement") between the Borrower and the Bank. Capitalized terms
used herein which are defined in the Credit Agreement have the same meanings
herein as therein, except to the extent that such meanings are amended hereby.

2)      AMENDMENTS.

        The Borrower and the Bank agree that the Credit Agreement is hereby
amended, effective as of the date hereof, as follows:

        a) Section 1.1 of the Credit Agreement is amended by amending the
        definition of Consolidated EBITDA to read as follows:

        "Consolidated EBITDA" means, for any period, the sum of (a) Consolidated
        Net Income of the Borrower and its Subsidiaries, if any, (determined in
        accordance with GAAP), plus (b) the consolidated income tax expense and
        consolidated Interest Expense of the Borrower and its Subsidiaries, if
        any, plus, (c) consolidated depreciation and amortization expenses of
        the Borrower and its Subsidiaries, if any, plus (d) other consolidated
        non-cash charges of the Borrower and its Subsidiaries and for the fiscal
        quarter ending December 2001 the cash reserve items listed on Schedule
        EBITDA, if any, minus (e) other consolidated non-cash credits of the
        Borrower and its Subsidiaries, if any (provided that all of the
        forgoing shall



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<PAGE>
        be calculated without reference to any extraordinary and unusual gain
        during such period).

        b) Section 2.8 (a) of the Credit Agreement is amended in its entirety to
        read as follows:

                (a) The Borrower agrees to pay to the Bank on the daily average
        unused amount of the respective Revolving Credit Commitment, during each
        fiscal quarter from and including the Closing Date any unused commitment
        fees equal to .50% per annum in each fiscal quarter that EBITDA is less
        than $8,000,000 and .375% per annum in each fiscal quarter that EBITDA
        is equal or greater than $8,000,000. Accrued commitment fees shall be
        payable in arrears on each Quarterly Date commencing on the first such
        date occurring after the date hereof. All commitment fees shall be
        computed on the basis of a year of 360 days and shall be payable for the
        actual number of days elapsed (including the first day but excluding the
        last day).

        c) Section 5.1 (b) of the Credit Agreement is amended in its entirety to
        read as follows:

                (b) as soon as available and in any event within 30 days after
        the end of each fiscal month of the Borrower statements of income,
        retained earnings and cash flows of the Borrower for such period and for
        the period from the beginning of the respective fiscal year to the end
        of such period and the related balance sheets of the Borrower as at the
        end of such period, setting forth in each case in comparative form the
        corresponding figures for the corresponding period in the preceding
        fiscal year (except that, in the case of balance sheets, such comparison
        shall be to the last day of the prior fiscal year) (provided that the
        Borrower shall deliver the reports under this Section 5.1 (b) (i) for
        each fiscal month in calendar year 2002 and thereafter until EBITDA for
        the last twelve months of the Borrower exceeds $8,000,000),

        d) Section 6.9 (b) of the Credit Agreement is amended in its entirety to
        read as follows:

                (b) Revolving Incurrence Test: The Bank shall not advance any
                additional Loan during any of the periods set forth below unless
                a Senior Officer can certify at the time the Loan is requested
                that the Consolidated EBITDA equals or exceeds the following
                minimums:

<TABLE>
<CAPTION>
        -----------------------------------------------------------------------
        Period                                Minimum Consolidated EBITDA
        -----------------------------------------------------------------------
<S>                                           <C>
        First Fiscal Quarter of Fiscal Year   $5,600,000
        2001 for the four fiscal quarter
        then ended
        -----------------------------------------------------------------------
        Second Fiscal Quarter of Fiscal       $5,900,000
        Year 2001 for the four fiscal
        quarter then ended
        -----------------------------------------------------------------------
        Third Fiscal Quarter of Fiscal Year   $6,500,000
        -----------------------------------------------------------------------
</TABLE>



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<PAGE>

<TABLE>
<S>                                           <C>
        -----------------------------------------------------------------------
        2001 for the four fiscal
        quarters then ended.
        -----------------------------------------------------------------------
        Fourth Fiscal Quarter of Fiscal       $6,400,000
        Year 2001 for the four fiscal
        quarter then ended
        -----------------------------------------------------------------------
        First Fiscal Quarter of Fiscal Year   $6,500,000
        2002 and each Fiscal Quarter thereafter
        for the four fiscal quarters
        then ended
        -----------------------------------------------------------------------
</TABLE>


        e) Section 6.9 (e) of the Credit Agreement is amended in its entirety to
        read as follows:

                (e) Minimum EBITDA. The Borrower shall have minimum Consolidated
                EBITDA at the end of each fiscal period as follows:


<TABLE>
<CAPTION>
        Fiscal Period                                   Minimum EBITDA
        -------------                                   --------------
<S>                                                     <C>
        Fourth Fiscal Quarter of Fiscal                 $5,000,000
        Year 2000 for the four fiscal
        quarters then ended.


        First Fiscal Quarter of Fiscal                  $5,000,000
        Year 2001 for the four fiscal
        quarters then ended.

        Second Fiscal Quarter of Fiscal                 $5,500,000
        Year 2001 for the four fiscal
        quarters then ended.

        Third Fiscal Quarter of Fiscal                  $6,500,000
        Year 2001 for the four fiscal
        quarters then ended. and at the
        end of each fiscal quarter
        thereafter for the four fiscal
        quarters then ended.

        Fourth Fiscal Quarter of Fiscal                 $6,400,000
        Year 2001 for the four fiscal
        quarters then ended.

        First Fiscal Quarter of Fiscal                  $6,500,000
        Year 2002 and each Fiscal
        Quarter thereafter for the four
        fiscal quarter then ended.
</TABLE>

        f) Section 6.9 (f) is added to the Credit Agreement to read as follows:

        (f) Application Against Cash Reserve. Borrower may expend no more than
        $1,500,000 each fiscal year against the cash reserve created under
        Schedule EBITDA and only for expenditures related to reserve items
        listed in such Schedule EBITDA as cash reserves.



                                      -3-
<PAGE>

3)      AFFIRMATION OF SECURITY AGREEMENTS AND INTELLECTUAL PROPERTY SECURITY
        AGREEMENTS.

        a) The Borrowers affirm that the Security Agreements (as defined in the
        Credit Agreement) remain in full force and effect and secure all of the
        Obligations either current or future due to the Bank.

        b) The Borrower has delivered this date revised Perfection Certificates
        in the form appended hereto as Exhibit A for each of them, which are
        true and correct.

        c) The Borrowers affirm that the Intellectual Property Security
        Agreements (as defined in the Credit Agreement) remain in full force and
        effect and secure all of the Obligations either current or future due to
        the Bank.

        d) The Borrowers have delivered this date revised Schedules for the
        Intellectual Property Security Agreement, which are true and correct.

4)      NO DEFAULT; REPRESENTATIONS AND WARRANTIES, ETC.

        The Borrower hereby confirms that: (a) the representations and
warranties of the Borrower contained the Credit Agreement are true on and as of
the date hereof as if made on such date (except to the extent that such
representations and warranties expressly relate to an earlier date), as modified
by any amendment of Schedules presented herewith; (b) the Borrower is in
compliance in all material respects with all of the terms and provisions set
forth in the Credit Agreement on their part to be observed or performed; and (c)
after giving effect to this Amendment, no Event of Default, nor any event which
with the giving of notice or expiration of any applicable grace period or both
would constitute such an Event of Default, shall have occurred and be
continuing.

5)      CONDITIONS TO THIS AMENDMENT.

        This Fourth Amendment shall not become effective until the date on which
each of the following conditions is satisfied:

        a) Counterparts of Agreement. The Bank shall have received from each
        party hereto a counterpart of this Agreement signed on behalf of such.

        b) Corporate Matters. The Bank shall have received such documents and
        certificates as the Bank may reasonably request relating to the
        organization, existence and good standing of the Borrower, the
        authorization of the Transactions and any other legal matters relating



                                      -4-
<PAGE>

        to the Borrower, this Agreement, the other Loan Documents or the
        Transactions, all in form and substance reasonably satisfactory to the
        Bank and its counsel.

        c) Perfection Certificates. The Borrower has delivered to the Bank
        updated Perfection Certificates

        d) Fees and Expenses. The Bank shall have received all fees and other
        amounts due and payable at or prior to the Closing Date, including, all
        out-of-pocket expenses required to be reimbursed or paid by the Borrower
        hereunder (including reasonable attorneys' fees and costs).

        e) Other Documents. The Bank shall have received such other documents as
        the Bank and its counsel shall have reasonably requested.

6)      MISCELLANEOUS.

        a) Except to the extent specifically amended hereby, the Credit
        Agreement, the Loan Documents and all related documents shall remain in
        full force and effect. Whenever the terms or sections amended hereby
        shall be referred to in the Credit Agreement, Loan Documents or such
        other documents (whether directly or by incorporation into other defined
        terms), such defined terms shall be deemed to refer to those terms or
        sections as amended by this Amendment.

        b) This Amendment may be executed in any number of counterparts, each of
        which, when executed and delivered, shall be an original, but all
        counterparts shall together constitute one instrument.

        c) This Amendment shall be governed by the laws of the Commonwealth of
        Massachusetts and shall be binding upon and inure to the benefit of the
        parties hereto and their respective successors and assigns.

        IN WITNESS WHEREOF, the parties hereto have executed this Amendment
        which shall be deemed to be a sealed instrument as of the date first
        above written.


                                        RUBIO'S RESTAURANTS, INC.


                                        By
                                           -------------------------------------
                                        Name:  Ralph Rubio
                                        Title: President



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<PAGE>

                                        RUBIO'S RESTAURANTS OF NEVADA, INC.

                                        By
                                           -------------------------------------
                                        Name:  Ted Frumkin
                                        Title: President

                                        FLEET NATIONAL BANK
                                        formerly known as BankBoston, N.A.

                                        By
                                           -------------------------------------
                                        Name:  Thomas Tansi
                                        Title: Director



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<PAGE>

                                                                 SCHEDULE EBITDA

                                   MARKET RATIONALIZATION PROJECT
                                       ONE TIME RESERVE DETAIL

AMTS IN 000'S

<TABLE>
<CAPTION>
                                                          ONE TIME           BOOKED
                                                           RESERVE             IN
                                                          --------           ------
<S>                                                       <C>                <C>
      - FAS121 writedown                                   $  (3,219)          Q3

      - Writedown Las Vegas in order to franchise               (838)          Q3

      - Writedown Salt Lake in order to franchise               (323)          Q3

      - Writedown Tucson in order to franchise                  (884)          Q3

      - Writedown Denver in order to franchise                (1,046)          Q3

        ONE TIME CHARGE IN THIRD QUARTER                   $  (6,310)
                                                           =========
      - Close 11 stores in November                           (3,171)          Q4

      - Close additional 4 stores in next 12 months           (1,259)          Q4

      - Store Closure Severance                                 (171)          Q4

      - Reduction-in-force Severance                            (151)          Q4

      - Franchise Transfer Retention payment                    (187)          Q4

      - Reserve for Signage Change (13 stores at $10K
        each)                                                   (130)          Q4

      - Reserve for Franchise Broker Fees                        (80)          Q4

      - Aurora lease termination                                (150)          Q4

      - Legal costs                                              (48)          Q4

      - Deferred Rent reversal                                    267          Q4

      - Employee travel to close markets & other support        (35)           Q4

        ESTIMATED ONE TIME CHARGE IN FOURTH QUARTER        $  (5,114)
                                                           =========
        TOTAL                                              $ (11,424)
                                                           =========
</TABLE>


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