EXHIBIT 99.1

                                                                  April __, 2005

TO:    Directors and Section 16 Officers of
       UnionBanCal Corporation

FROM:      John H. McGuckin, Jr.
           EVP, General Counsel & Secretary

                    NOTICE OF BLACKOUT PERIOD FOR 401(K) PLAN

     o   This notice is required pursuant to the Sarbanes-Oxley Act

     o   You may not  conduct  transactions  in  UnionBanCal  equity  securities
         during the "blackout  period"  described  below that we expect to begin
         May 2, 2005 and end May 13, 2005, except that you may make gifts during
         this period.

     o   You are also subject to the  UnionBanCal  insider  trading  policy that
         restricts   your  ability  to  conduct   transactions   in  UnionBanCal
         securities  except during window periods.  The window is now closed and
         the next  window  period is  scheduled  for the period  April 25,  2005
         through and including April 29, 2005.

This is to notify you of an  upcoming  blackout  period  under the Union Bank of
California,  N.A.  401(k)  Plan and Trust  (the  "Plan").  During  this  trading
blackout,  your ability to conduct transactions in UnionBanCal equity securities
will be limited.  We expect the blackout period to begin May 2, 2005 and end May
13, 2005.

The  blackout  period  will  allow  the Plan make  changes  in  investment  fund
selections. During the blackout period, participants will be unable to direct or
diversify  investments in their individual accounts or obtain a loan, withdrawal
or  distribution  from the  Plan.  Participants  in the Plan have  already  been
notified of the blackout period.

In addition,  because the Plan offers  UnionBanCal common stock as an investment
option,  pursuant to Section 306 of the  Sarbanes-Oxley  Act of 2002 UNIONBANCAL
DIRECTORS  AND SECTION 16 OFFICERS  ARE NOT  PERMITTED  TO TRADE IN  UNIONBANCAL
EQUITY  SECURITIES  WHILE PLAN  PARTICIPANTS ARE UNABLE TO TRANSACT IN THE PLAN.
This means that except as provided in the next  paragraph,  during the  blackout
period you may not directly or indirectly  purchase,  sell, or otherwise acquire
or transfer any  UnionBanCal  equity  securities  (INCLUDING THE EXERCISE OF ANY
OPTIONS  OR THE SALE OF ANY  RESTRICTED  STOCK).  This  prohibition  applies  to
UnionBanCal equity securities you hold both inside and outside the Plan.

Gifts,  dividend  reinvestments  under a dividend  reinvestment plan and trading
pursuant to a 10b5-1 trading plan are exempt from this prohibition.

Please note that the  restrictions  described  in this notice are in addition to
the  normal  restrictions  on  trading  activity  that  UnionBanCal  imposes  on
directors and executive officers.  In particular,



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you  continue to be subject to the  UnionBanCal  insider  trading  policy  which
prohibits most transactions until the next window period.

If you have any  questions  with  respect to this notice,  please  contact me at
(415)  765-2969.


John H. McGuckin, Jr.
EVP, General Counsel & Secretary
UnionBanCal Corporation
400 California Street
San Francisco, CA 94104-1302




























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