<PAGE>

                                                                    EXHIBIT 10.2

                      FIRST AMENDMENT TO CREDIT AGREEMENT

          This FIRST AMENDMENT TO CREDIT AGREEMENT (this "Amendment"), made and
entered into as of October 21, 1999, is by and between BUCA, INC., a Minnesota
corporation (the "Borrower"), the banks which are signatories hereto
(individually, a "Bank" and, collectively, the "Banks"), BANK OF AMERICA, N.A.,
a national banking association, one of the Banks and as co-agent for the Banks
(in such capacity, a "Co-Agent"), BANKBOSTON, N.A., a national banking
association, as one of the Banks and as co-agent for the Banks (in such
capacity, a "Co-Agent") and U.S. BANK NATIONAL ASSOCIATION, a national banking
association, one of the Banks, as agent for the Banks (in such capacity, the
"Agent").

                                 RECITALS
                                 --------

          1.  U.S. Bank National Association, as Agent and as a Bank, and Bank
of America, N.A., as Co-Agent and as a Bank (the "Existing Banks"), and the
Borrower entered into a Credit Agreement dated as of September 27, 1999 (the
"Credit Agreement"); and

          2.  The Borrower has requested that the Existing Banks, together with
the BankBoston, N.A., increase the credit facility and amend the Credit
Agreement in certain respects.

          3.  The parties desire to amend the Credit Agreement,  subject to the
terms and conditions set forth in this Amendment.

                                 AGREEMENT
                                 ---------

          NOW, THEREFORE, for good and valuable consideration, the receipt and
adequacy of which are hereby acknowledged, the parties hereto hereby covenant
and agree to be bound as follows:

          Section 1.  Capitalized Terms.  Capitalized terms used herein and not
                      -----------------
otherwise defined herein shall have the meanings assigned to them in the Credit
Agreement, unless the context shall otherwise require.

          Section 2.  Amendment.  The Credit Agreement is hereby amended as
                      ---------
follows:

          2.1  Parties.  BankBoston, N.A. is hereby added as a party and
               -------
     signatory to the Credit Agreement, in the capacity as a Bank and Co-Agent
     thereunder.

          2.2  Definitions.  The following definitions are added in alphabetical
               -----------
     order to Section 1.1 of the Credit Agreement.
<PAGE>

          "BofA"  Bank of America, N.A., a national banking association.
           ----

          "BankBoston"  BankBoston, N.A., a national banking association.
           ----------

          The definition of "Co-Agent" in Section 1.1 of the Credit Agreement is
                             --------
          amended in its entirety to read as follows:

               "Co-Agent": Each of BofA and BankBoston.
                --------

          2.3  Modifications.  Section 9.1(d) of the Credit Agreement is amended
               -------------
     in its entirety to read as follows:

               9.1(d)  Except as may otherwise be expressly provided in any of
          the other Loan Documents as such documents are amended as of October
          21, 1999, release any material portion of collateral securing, or any
          guaranties for, all or any part of the Obligations without the consent
          of all the Banks; or

          2.4  Modifications.  Section 9.1(g) of the Credit Agreement is amended
               ------------
     in its entirety to read as follows:

               9.1(g) Amend Section 9.1(f) or this Section 9.1(g) without the
          consent of the Agent, USBNA (so long as it is a Bank), BofA (so long
          as it is a Bank), BankBoston (so long as it is a Bank) and each Co-
          Agent; or

          2.5  New Restaurants.  Section 5.19 is amended by deleting the word
               ---------------
     "Bank" in the fourth line thereof and substituting the word "Agent"
     therefor.

          2.6  Signature pages.  The signature pages to the Credit Agreement are
               ---------------
     hereby deleted and inserted in lieu thereof are the signature pages as set
     forth on Exhibit A attached to this Amendment.

          Section 3.  Effectiveness of Amendments.  The amendments contained in
                      ---------------------------
this Amendment shall become effective upon delivery by the Borrower of, and
compliance by the Borrower with, the following:

          3.1  This Amendment and the Notes in favor of BankBoston (the
     "BankBoston Notes"), each duly executed by the Borrower.

          3.2  A Consent and Reaffirmation in the form of Exhibit B-1 and B-2
     attached to this Amendment, duly executed by each of the Guarantors shown
     as a signatory thereto.
<PAGE>

         3.3  A copy of the resolutions of the Board of Directors of (a) the
     Borrower authorizing the execution, delivery and performance of this
     Amendment and the BankBoston Notes and (b) each Guarantor authorizing the
     execution delivery and performance of its respective consent and
     reaffirmation, and in each case, certified as true and accurate by its
     Secretary or Assistant Secretary, along with a certification by such
     Secretary or Assistant Secretary (i) certifying that there has been no
     amendment to the Articles of Incorporation or Bylaws of the Borrower or the
     respective Guarantor since true and accurate copies of the same were
     delivered to the Agent with a certificate of the Secretary of the Borrower
     and each of the Guarantors dated September 27, 1999, and (ii) (A) in the
     case of the Borrower, identifying the officer of the Borrower authorized to
     execute this Amendment, the BankBoston Notes and any other instrument or
     agreement executed by the Borrower in connection with this Amendment
     (collectively, the "Amendment Documents"), and (B) in the case of each
     Guarantor, identifying the officer authorized to execute its respective
     Consent and Reaffirmation and any other instrument or agreement executed by
     the such Guarantor in connection with this Amendment, and certifying as to
     specimens of such officer's signature and such officer's incumbency in such
     offices as such officer holds.

          3.4  A First Amendment to Pledge Agreement, duly executed by the
     Borrower, together with the delivery of the certificate representing all of
     the Borrower's shares of stock in BUCA (DT Minneapolis), Inc. and
     accompanied by a duly executed instrument of transfer or assignment in
     blank of said certificate, all in form and substance satisfactory to the
     Agent.

          3.5  An opinion of counsel to the Borrower and the Guarantors in form
     and substance satisfactory to the Agent.

          3.6  Payment by the Borrower of a facility fee of $25,000 to the Agent
     for the account of BankBoston, N.A.

          3.7  Payment of all reasonable unpaid legal fees and other out-of-
     pocket expenses incurred by the Agent through the date of this Amendment in
     connection with the Amendment Documents of which the Borrower has been
     notified as of the date of this Amendment.

          Section 4.  Representations, Warranties, Authority, No Adverse Claim.
                      --------------------------------------------------------

          4.1  Reassertion of Representations and Warranties, No Default.  The
               ---------------------------------------------------------
Borrower hereby represents that on and as of the date hereof and after giving
effect to this Amendment (a) all of the representations and warranties contained
in the Credit Agreement are true and correct in all respects as of the date
hereof as though made on and as of such date, except for changes permitted by
the terms of the Credit Agreement, and (b) there will exist no
<PAGE>

Default or Event of Default under the Credit Agreement as amended by this
Amendment on such date which has not been waived by the Agent.

          4.2  Authority, No Conflict, No Consent Required. The Borrower
               -------------------------------------------
represents and warrants that the Borrower has the corporate power and authority
to enter into the Amendment Documents and has duly authorized the execution and
delivery of the Amendment Documents and other agreements and documents executed
and delivered by the Borrower in connection herewith or therewith by proper
corporate action, and, except as set forth in Schedule 4.3 to the Credit
Agreement, none of the Amendment Documents nor the agreements contained herein
or therein contravenes or constitutes a default under any agreement, instrument
or indenture to which the Borrower is a party or a signatory or a provision of
the Borrower's Articles of Incorporation, Bylaws or any requirement of law
presently in effect or that is applicable to the Borrower, or result in the
imposition of any Lien on any of its property under any agreement binding on or
applicable to the Borrower or any of its property except, if any, in favor of
the Agent and except where the contravention or default or the imposition of
such Lien could not adversely effect the validity or enforceability of the
Amendment Documents or constitute a Material Adverse Occurrence.  The Borrower
represents and warrants that, except as set forth in Schedule 4.3 to the Credit
Agreement, no consent, approval or authorization of or registration or
declaration with any Person, including but not limited to any governmental
authority, is required on the part of the Borrower in connection with the
execution and delivery by the Borrower of the Amendment Documents or other
agreements and documents executed and delivered by the Borrower in connection
therewith or the performance of obligations of the Borrower therein described,
except for those which the Borrower has obtained or provided and as to which the
Borrower has delivered certified copies of documents evidencing each such action
to the Agent and except where the failure to obtain such consent, approval or
authorization or to make such registration or declaration could not adversely
effect the validity or enforceability of the Amendment Documents or constitute a
Material Adverse Occurrence.

          4.3  No Adverse Claim. The Borrower warrants, acknowledges and agrees
               ----------------
that to the Borrower's knowledge no events have been taken place and no
circumstances exist at the date hereof which would give the Borrower a basis to
assert a defense, offset or counterclaim to any claim of the Banks with respect
to the Borrower's obligations under the Credit Agreement as amended by this
Amendment.

          Section 5.  Affirmation of Credit Agreement, Further References,
                      ----------------------------------------------------
Affirmation of Security Interest.  The Banks and the Borrower each acknowledge
--------------------------------
and affirm that the Credit Agreement, as hereby amended, is hereby ratified and
confirmed in all respects and all terms, conditions and provisions of the Credit
Agreement, except as amended by this Amendment, shall remain unmodified and in
full force and effect.  All references in any document or instrument to the
Credit Agreement are hereby amended and shall refer to the Credit Agreement as
amended by this Amendment.   The Borrower confirms to the Banks that the
Borrower's obligations under the Credit Agreement, as amended by this Amendment,
are and continue to be secured by the security interest granted by the Borrower
in favor of the Agent
<PAGE>

under the Security Agreement, that certain Pledge Agreement, and that certain
Collateral Assignment of Trademarks, all dated as of September 27, 1999, and
made by the Borrower in favor of the Banks, and all of the terms, conditions,
provisions, agreements, requirements, promises, obligations, duties, covenants
and representations of the Borrower under such documents and any and all other
documents and agreements entered into with respect to the obligations under the
Credit Agreement are incorporated herein by reference and are hereby ratified
and affirmed in all respects by the Borrower.

          Section 6. Successors.  The Amendment Documents shall be binding upon
                     ----------
the Borrower and the Banks and their respective successors and assigns, and
shall inure to the benefit of the Borrower and the Banks and the successors and
assigns of the Banks.

          Section 7. Legal Expenses.  As provided in Section 9.2 of the Credit
                     --------------
Agreement, the Borrower agrees to reimburse the Agent, upon execution of this
Amendment, for all reasonable out-of-pocket expenses (including reasonable
attorney's fees and legal expenses of Dorsey & Whitney LLP, counsel for the
Agent) incurred in connection with negotiation, preparation and execution of the
Amendment Documents and all other documents negotiated, prepared and executed in
connection with the Amendment Documents, and in enforcing the obligations of the
Borrower under the Amendment Documents, and to pay and save the Banks harmless
from all liability for, any stamp or other taxes which may be payable with
respect to the execution or delivery of the Amendment Documents, which
obligations of the Borrower shall survive any termination of the Credit
Agreement.

          Section 8. Counterparts.  The Amendment Documents may be executed in
                     ------------
several counterparts as deemed necessary or convenient, each of which, when so
executed, shall be deemed an original, provided that all such counterparts shall
be regarded as one and the same document, and any party to the Amendment
Documents may execute any such agreement by executing a counterpart of such
agreement.

          Section 9. Governing Law.  THE AMENDMENT DOCUMENTS SHALL BE GOVERNED
                     -------------
BY THE INTERNAL LAWS OF THE STATE OF MINNESOTA, WITHOUT GIVING EFFECT TO
CONFLICT OF LAW PRINCIPLES THEREOF, BUT GIVING EFFECT TO FEDERAL LAWS APPLICABLE
TO NATIONAL BANKS, THEIR HOLDING COMPANIES AND THEIR AFFILIATES.
<PAGE>

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

BORROWER:                               BUCA, INC.


                                        By: /s/ Greg A. Gadel
                                           -------------------------------

                                        Title: Chief Financial Officer
                                              ----------------------------

                                        Address:
                                        Attention:  Greg A. Gadel
                                        1300 Nicollet Avenue
                                        Suite 3043
                                        Minneapolis, MN 55403
                                        Telephone No.: (612) 288-2382
                                        Telecopier No.: 612) 827-6446

AGENT:                                  U.S. BANK NATIONAL ASSOCIATION

                                        By: /s/ Joshua R. Pirozzolo
                                           ------------------------------
                                        Title: Commercial Banking Officer
                                              ---------------------------
                                        Address: Attention: Joshua R. Pirozzolo
                                        601 Second Avenue South
                                        Minneapolis, MN 55402-4302
                                        Telephone No.: (612) 973-0520
                                        Telecopier No.: (612) 973-0823

                                      S-1
                       Signature Page to First Amendment
<PAGE>

CO-AGENT:                     BANK OF AMERICA, N.A.

                              By: /s/ William S. Richards, Jr.
                                 --------------------------------------------

                              Title: Vice President
                                    -----------------------------------------
                              Address:  Attention:  William S. Richards, Jr.
                              IL1-231-06-13
                              231 South LaSalle Street
                              Chicago, IL 60697

                              Telephone No.:  (312) 828-2731
                              Telecopier No.:  (312) 828-1974


CO-AGENT:                     BANKBOSTON, N.A.

                              By: /s/ Rod Quinn
                                 --------------------------------------------
                              Title: Division Executive
                                    -----------------------------------------
                              Address:
                              Attention: Christopher M. Holtz
                              MS 01-09-05
                              100 Federal Street
                              Boston, MA 02110
                              Telephone No.:  (617) 434-7690
                              Telecopier No.:  (617) 434-0630



                                      S-2
                       Signature Page to First Amendment
<PAGE>

                                                                       EXHIBIT A
                                                              TO FIRST AMENDMENT
                                                             TO CREDIT AGREEMENT



                          See attached Signature Pages
<PAGE>

          IN WITNESS WHEREOF, the parties hereto have caused this Agreement to
be executed as of the date first above written.

                              BUCA, INC.


                              By      /s/  Greg A. Gadel
                                ---------------------------------------
                              Title   Chief Financial Officer
                                   ------------------------------------

                              Address:
                              Attention: Greg A. Gadel
                              1300 Nicollet Avenue
                              Suite 3043
                              Minneapolis, MN 55403

                             Telephone No.: (612) 288-2382
                             Telecopier No.: (612)  827-6446




Revolving (A) Commitment
 Amount:                     U.S. BANK NATIONAL ASSOCIATION,
$3,333,333.34                in its individual corporate capacity and as Agent

Revolving (B) Commitment
 Amount:
$1,666,666.67                By      /s/  Joshua R. Pirozzolo
                                ----------------------------------------
                             Title    Commercial Banking Officer
                                   -------------------------------------

                             Address:
                             Attention: Joshua R. Pirozzolo  MPFP0602
                             601 Second Avenue South
                             Minneapolis, MN 55402-4302

                             Telephone No.: (612) 973-0520
                             Telecopier No.: (612) 973-0823

                                     S-1
<PAGE>

Revolving (A) Commitment
 Amount:                    BANK OF AMERICA, N.A.
$3,333,333.33               in its individual corporate
                            capacity and as Co-Agent
Revolving (B) Commitment
 Amount:
$1,666,666.67
                            By  /s/  William S. Richards, Jr.
                               -----------------------------------------
                            Its          Vice President
                                ----------------------------------------

                            Address:
                            Attention: William S. Richards, Jr.
                            IL1-231-06-13
                            231 South LaSalle Street
                            Chicago, IL 60697
                            Telephone No.: (312) 828-2731
                            Telecopier No.: (312) 828-1974


Revolving (A) Commitment
 Amount:                    BANKBOSTON, N.A.
$3,333,333.33               in its individual corporate
                            capacity and as Co-Agent
Revolving (B) Commitment
 Amount:
$1,666,666.66
                            By      /s/   Rod Quinn
                              ---------------------------------------
                            Its       Division Executive
                                -------------------------------------

                            Address:
                            Attention: Christopher M. Holtz
                            MS 01-09-05
                            100 Federal Street
                            Boston, MA 02110
                            Telephone No.: (617) 434-7690
                            Telecopier No.: (617) 434-0630

                                      S-2