EXHIBIT 5.1

                          PILLSBURY MADISON & SUTRO LLP
                              235 Montgomery Street
                             San Francisco, CA 94104
                               Tel: (415) 983-1000


June 14, 1999




SJNB Financial Corp.
One North Market Street
San Jose, CA  95113


         Re:      Registration Statement on Form S-8


Gentlemen:

     With  reference  to the  Registration  Statement on Form S-8 to be filed by
SJNB  Financial  Corp.,  a  California  corporation  (the  "Company"),  with the
Securities and Exchange Commission under the Securities Act of 1933, relating to
150,000 shares of the Company's Common Stock issuable  pursuant to the Company's
1996 Stock Option Plan,  as amended (the "Stock  Plan"),  it is our opinion that
such  shares  of the  Common  Stock  of the  Company,  when  issued  and sold in
accordance  with  the  Stock  Plan,  will be  legally  issued,  fully  paid  and
nonassessable.

     We hereby  consent to the filing of this  opinion with the  Securities  and
Exchange Commission as Exhibit 5.1 to the Registration Statement.

Very truly yours,

/s/Pillsbury Madison & Sutro LLP