Exhibit 5.1

                                December 27, 2001

Greater Bay Bancorp
2860 West Bayshore Road
Palo Alto, California 94303

               Re:  Greater Bay Bancorp 1996 Stock Option Plan, as amended (the
"Plan")

Ladies and Gentlemen:

               As General Counsel of Greater Bay Bancorp (the "Company"), at
your request, I have examined the Registration Statement on Form S-8 (the
"Registration Statement") being filed by the Company with the Securities and
Exchange Commission in connection with the registration under the Securities Act
of 1933, as amended, of up to 4,000,000 additional shares of the Company's
common stock, no par value (the "Shares"), that may be issued in the aggregate
under the Plan.

               In rendering this opinion, I have examined and reviewed only such
questions of law as I have deemed necessary or appropriate for the purpose of
rendering the opinions set forth herein. For the purpose of rendering the
opinions set forth herein, I have been furnished with and examined only the
following documents:

               1.   The Articles of Incorporation of the Company, as amended.

               2.   The Bylaws of the Company, as amended.

               3.   The Registration Statement.

               4.   Records of proceedings of the Board of Directors and
                    shareholders of the Company pertaining to the Plan.

               5.   The Plan.

               With respect to all of the foregoing documents, I have assumed
the genuineness of all signatures, the authenticity of all documents submitted
to us as originals and the conformity to originals of all documents submitted to
us as certified or reproduced copies. I also have obtained from the officers of
the Company certificates as to such factual matters as I consider necessary for
the purpose of this opinion, and insofar as this opinion is based on such
matters of fact, I have relied on such certificates.

               Based upon the foregoing and such further review of fact and law
as I have deemed necessary or appropriate under the circumstances, and assuming,
without further inquiry other than such certificates of officers, that (i) the
consideration for the shares of Common Stock issued pursuant to the exercise of
such options will be received prior to the issuance thereof, (ii) the Common
Stock issued pursuant to the exercise of options will be issued in accordance
with the terms of the Plan and the various agreements and (iii) the grant of
such options and the



issuance of Shares upon the exercise thereof will comply with the securities
laws of each state or jurisdiction applicable thereto (other than the Securities
Act of 1933, as amended, as to which this opinion is addressed), upon which
assumptions the opinions contained herein are expressly conditioned, I am of the
opinion that:

               If, as and when the Shares have been issued and sold pursuant to
exercise of options granted under the terms of the Plan, the Shares will be duly
authorized, validly issued, fully paid and non-assessable.

               This opinion is issued to you solely for use in connection with
the Registration Statement on Form S-8 and is not to be quoted or otherwise
referred to in any financial statements of the Company or related document, nor
is it to be filed with or furnished to any government agency or other person,
without my prior written consent.

               This opinion is limited to the current laws of the State of
California and the United States of America, to present judicial interpretations
thereof and to facts as they presently exist. In rendering this opinion, I have
no obligation to revise or supplement it should the current laws of the State of
California or the United States of America be changed by legislative action,
judicial decision or otherwise.

               I hereby consent to the filing of this opinion as an exhibit to
the Registration Statement on Form S-8 which is being filed on behalf of the
Company in connection with the registration of the aforementioned Shares under
the Securities Act of 1933, as amended.

                                      Very truly yours,

                                      /s/Linda M. Iannone

                                      Senior Vice President, General Counsel and
                                      Secretary of Greater Bay Bancorp