EXHIBIT 8

                       Letterhead of Bingham McCutchen LLP
                            Three Embarcadero Center
                         San Francisco, California 94111


September 13, 2002




Union Bank of California, N.A.
400 California Street
San Francisco, California 94101

Valencia Bank & Trust
24300 Town Center Drive, Suite 100
Valencia, California 91355

MERGER OF VALENCIA BANK & TRUST WITH UNION BANK OF CALIFORNIA

Ladies and Gentlemen:

You have asked for our opinion as to certain federal income tax  consequences of
the  proposed  merger (the  "Merger")  of Valencia  Bank & Trust,  a  California
banking corporation ("Valencia") and Union Bank of California,  N.A. ("UBOC"), a
national  banking   association  and  wholly-owned   subsidiary  of  UnionBanCal
Corporation, a California corporation  ("UnionBanCal").  The terms of the Merger
are set forth in the Agreement and Plan of Merger dated as of August 5, 2002, to
which Valencia, UBOC and UnionBanCal are parties (the "Agreement"). This opinion
is  delivered to you pursuant to Section  6.3(d) of the  Agreement.  Capitalized
terms used in this letter without definition have the respective  meanings given
them in the Agreement.

The  Agreement  provides  that Valencia will be merged with and into UBOC at the
Effective  Time pursuant to the  applicable  provisions of the National Bank Act
and the  California  General  Corporation  Law.  In the  Merger,  the issued and
outstanding  shares of Valencia  stock (other than shares of Valencia  stock for
which  dissenters'  rights are  perfected)  will be converted  into the right to
receive  from  UnionBanCal  the UB Common  Stock  and/or cash  described  in the
Agreement.

For purposes of rendering this opinion we have examined and relied upon (without
any independent investigation or review) the truth, correctness and completeness
at  all  relevant  times  of  the  statements,  covenants,  representations  and
warranties  contained  in  the  Agreement  and  in  the  Officer's  Certificates
delivered  to us by Valencia and  UnionBanCal,  and such other  instruments  and
documents as we have deemed necessary.






Union Bank of California, N.A.
Valencia Bank & Trust
September 13, 2002
Page 2



Further,  for  purposes of  rendering  this  opinion we have made the  following
assumptions (without any independent investigation or review):

1. Original  documents  submitted to us (including  signatures)  are  authentic,
documents  submitted to us as copies  conform to the original  documents and all
such  documents  either  have  been or will be by the  Effective  Time  duly and
validly   executed  and  delivered   where  such   execution  and  delivery  are
prerequisites to effectiveness;

2. All facts, statements, covenants, representations and warranties contained in
any of the  documents  referred to herein or otherwise  made to us in connection
with the Merger are true,  correct and  complete in all  respects as of the date
hereof  and  will be  true,  correct  and  complete  in all  respects  as of the
Effective  Time,  and no  actions  have  been  (or  will  be)  taken  which  are
inconsistent  with  such  facts,  statements,  covenants,   representations  and
warranties;

3. The Merger will be consummated in accordance  with the terms of the Agreement
and the Merger will be effective under applicable laws; and

4. The Merger  will be  reported  by  Valencia,  UBOC and  UnionBanCal  on their
respective  federal income tax returns in a manner  consistent  with the opinion
set forth below.

Based upon our understanding of the transaction as described above and the above
assumptions,  and subject to the limitations contained herein, it is our opinion
that the Merger will constitute a  reorganization  within the meaning of Section
368(a)  of the  Code  and  that  no  gain or  loss  will  be  recognized  by the
shareholders of Valencia to the extent that they receive only UB Common Stock in
exchange for shares of Valencia  stock. In the event that any one or more of the
facts,  statements,  descriptions,  covenants,  representations,  warranties  or
assumptions  upon which we have relied to issue this opinion is  incorrect,  our
opinion might be adversely affected and may not be relied upon.

The opinion  expressed  herein is based upon  statutes,  judicial  decisions and
administrative  regulations,  rulings and practice, all as in effect on the date
hereof  and all of which are  subject  to  change,  either on a  prospective  or
retroactive  basis.  We do not  undertake  any  responsibility  for  updating or
revising  our opinion in  consequence  of any such  change.  We express only the
opinion set forth above.  This  opinion  does not address any other  federal tax
consequences  or any state,  local or foreign tax  consequences  that may result
from the Merger or any other transaction (including any transaction




Union Bank of California, N.A.
Valencia Bank & Trust
September 13, 2002
Page 3


contemplated   by  the  Agreement  or  undertaken  in  connection   with  or  in
contemplation of the Merger).

We  hereby  consent  to  the  filing  of  this  opinion  as an  exhibit  to  the
Registration  Statement of UnionBanCal on Form S-4 and the reference to the name
of our firm  therein  and under the caption  "Legal  Matters" in the Joint Proxy
Statement/Prospectus  furnished in connection with the offering of securities by
UnionBanCal  and the  solicitation  of  proxies  by the  Board of  Directors  of
Valencia.  In giving our  consent,  we do not  thereby  admit that we are in the
category of persons whose consent is required  under Section 7 of the Securities
Act or the rules and  regulations  of the  Securities  and  Exchange  Commission
thereunder.

Sincerely yours,

/s/Bingham McCutchen LLP
BINGHAM McCUTCHEN LLP