ADDENDUM NO. 3 TO LEASE

This is an Addendum to the Lease dated June 1, 1993 in which  BioTime,  Inc.,  a
California  corporation,  is referred to as "Lessee." The following  changes are
hereby incorporated. In the event of a conflict of terms, those of this Addendum
shall prevail.

1. The Premises are hereby expanded to include the entire building at 935 Pardee
Street, Berkeley, California being approximately 8890 square feet on two levels,
and its adjacent parking area. The additional  space,  comprising  approximately
3,000 square feet, is referred to as the "Expansion Space."

2. Regarding  Paragraph 1: The term shall be Five (5) years  commencing April 1,
1999.

3.  Regarding  Paragraph 2: Rent shall be Five  Thousand  Five  Hundred  Dollars
($5,500.00)  per month prior to  Lessor's  delivery  of the  Expansion  Space to
Lessee.  Upon Lessee's possession of the Expansion Space, rent shall increase to
Ten Thousand  Dollars  ($10,000.00)  per month for the entire  premises.  If the
Expansion  Space is  delivered  to Lessee on a day other than the first day of a
calendar  month,  the rent shall be prorated at the rate of  Thirty-Seven  Cents
($0.037) per square foot per day.

4.  Regarding  Paragraph  14:  Lessee  shall pay for all  utilities  and  refuse
collection.

5. Regarding  Paragraph 29: Rental for any holding over shall be Eleven Thousand
Dollars ($11,000.00) per month as stated in said paragraph.

6.  Regarding  Paragraph  33: On each  anniversary  of the lease,  rent shall be
increased  according  to the  increase in the  Consumer  Price Index  during the
previous year,  except that no single  increase shall be less than three percent
(3%) nor greater than seven percent (7%).  The Consumer Price Index shall be the
consumer  price  index  (All Urban  Consumers,  base year  1982-84=100)  for San
Francisco  Oakland - San Jose CMSA published by the United States  Department of
Labor, Bureau of Labor Statistics.

7. Regarding  Paragraph 34: Lessee shall have one (1) option to extend the lease
for an  additional  three (3) years on the same terms and  conditions  stated in
said paragraph.

8. Possession:  Lessor shall deliver possession of the Expansion Space to Lessee
June 30,  1999 or on such  earlier  date on which the  Expansion  Space  becomes
vacant and meets the conditions of Paragraph 9C of this Addendum.

9. Condition of Premises at  Commencement:  As-is  excepting the following which
shall be the Lessor's obligation:


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A.  Lessor  shall  inspect  wood  floors  on the  second  floor and  repair  and
strengthen as required.

B.  Lessor shall modify shed to provide for its use as a parking space.

C.  The  Expansion  Space shall be in good  condition  and  repair,  broom swept
         clean and free of all personal property, equipment, furniture and trade
         fixtures of the prior tenant.

10. Early  Termination:  At any time after the  expiration  of the eighteen (18)
month of the new lease  term,  Lessee may  terminate  the lease by so  notifying
Lessor in writing no less than six (6) months prior to the intended  termination
date.


/s/ Ronald S. Barkin                                         2/8/99
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 for BioTime, Inc., Lessee                                    Date


/s/ Donn Logan                                               2/8/99
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Lessor                                                        Date