Exhibit 99.1

                                  [LETTERHEAD]
                                Human BioSystems


July 19, 2005

Re:Human BioSystems Common Stock

Dear Human BioSystems Reg S Shareholder:

It has come to our attention that Reg S shares of the common stock of Human
BioSystems, a California corporation ("HBS"), may have been sold without the
authorization of HBS. The unauthorized issuance of HBS shares may have
tainted the market for those HBS shares previously issued under Regulation S
under the United States Securities Act of 1933, as amended, and currently
trading under WKN#164580 the ("Reg S Stock").

In order to halt these unauthorized issuances, we are undertaking an exchange
offer (the "Offer") to exchange one share of HBS common stock (the "New Stock")
for each share of Reg S Stock outstanding before or upon the de-listing date
(the "Record Date") when the Reg S Stock is no longer tradable. Each share of
New Stock will be registered no later than six months from the date hereof for
trading on the United States Over-the-Counter Bulletin Board market (the
"OTCBB").

In order to accept the Offer, you must return your Reg S stock to HBS, together
with a copy of the brokerage account receipt showing the date of purchase and
the number of shares of Reg S stock purchased.  Please instruct your broker/bank
to send your Reg S shares electronically to:

                            Account No. 725422-75-1
                      For the benefit of Human BioSystems
                                 Credit Suisse
                               Bahnhofstrasse 17
                                    CH-6301
                                Zug, Switzerland

Please fax your brokerage account receipt to Human BioSystems at (650) 327-8658,
indicating the name of the holder of the Reg S Stock and the number of shares
held. If possible please also include your telephone and fax number, and your
email address so that we may communicate with you if there are questions.

THIS EXCHANGE OFFER EXPIRES ON DECEMBER 29, 2005.  Human BioSystems reserves the
right to refuse to exchange any Reg S Stock of unauthorized origin.  Upon
receipt of the Reg S Stock and documentation indicating the purchase of
authorized Reg S Stock, we will send you a certificate for the same number of
shares of New Stock within 30 business days.  If shares of Reg S Stock, together
with the required documentation, are not tendered for exchange by December 29,
2005, they will no longer be exchangeable for New Stock.  In addition, as we
plan to de-list the Reg S Stock from trading on all German stock exchanges as
soon as possible following this news release, the Reg S Stock will no longer be
tradeable effective immediately upon such de-listing.

This Exchange Offer will also be submitted to Clearstream for distribution so
that we may reach as many Reg S Shareholders as possible.

Thank you for your investment in and support of Human BioSystems.  Due to your
investment, we have made significant progress toward achieving our goals to
date.

Please contact me if you have any questions or comments regarding this matter.

Very truly yours,


/s/ Harry Masuda
___________________________
    Harry Masuda
    President and CEO

cc:Cathryn S. Gawne, Esq.
Mr. Karsten Behrens Facsimile No.:  41 219 222 473
Clearstream