8-K

                         SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, D.C.  20549
                              ________________________
                                          
                                      FORM 8-K
                                          
                                   CURRENT REPORT
                       PURSUANT TO SECTION 13 OR 15(d) OF THE
                          SECURITIES EXCHANGE ACT OF 1934
                                          
         Date of Report (date of earliest event reported): October 15, 1998
                                          
                                  AFFYMETRIX, INC.
               (Exact name of registrant as specified in its charter)
                                          

           Delaware                   0-28218                 77-0319159
           --------                   -------                 ----------
 (State or other jurisdiction       (Commission            (I.R.S. Employer
       of incorporation)            File Number)         Identification No.)


                   3380 Central Expressway, Santa Clara, CA 95051
            (Address of principal executive offices, including zip code)
                                          
        Registrant's telephone number, including area code:  (408) 731-5000



ITEM 5.   OTHER EVENTS

          On October 15, 1998, the Board of Directors of Affymetrix, Inc. (the
"Company") declared a dividend of (i) one preferred share purchase right (a
"Right") for each outstanding share of common stock, par value $.01 per share,
of the Company (the "Common Stock"), and (ii) a number of Rights for each share
of Series AA Preferred Stock, par value $.01 per share, of the Company (the
"Series AA Preferred Stock") equal to the number of shares of Common Stock into
which such share of Series AA Preferred Stock was convertible at the close of
business on the Record Date (as hereinafter defined).  The dividend is payable
on October 27, 1998 (the "Record Date") to the stockholders of record on that
date.  Each Right entitles the registered holder to purchase from the Company
one one-thousandth of a share of Series B Junior Participating Preferred Stock,
par value $.01 per share, of the Company (the "Series B Preferred Stock") at a
price of $125.00 per one one-thousandth of a share of Series B Preferred Stock
(the "Purchase Price"), subject to adjustment.  The description and terms of the
Rights are set forth in a Rights Agreement dated as of October 15, 1998, as the
same may be amended from time to time (the "Rights Agreement"), between the
Company and American Stock Transfer & Trust Company, as Rights Agent (the
"Rights Agent").  
          
          A summary of the terms of the Rights Agreement is attached as an
exhibit hereto.  A copy of the Rights Agreement has been filed with the
Securities and Exchange Commission as an Exhibit to a Registration Statement on
Form 8-A dated October 16, 1998.  



ITEM 7.   EXHIBITS

          Exhibit
          Number         Description
          -------        -----------
          3.3            Summary of Rights to Purchase Shares of Preferred Stock
                         pursuant to the Rights Agreement dated as of 
                         October 15, 1998.



                                     SIGNATURES
                                          

        Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.


                                      Affymetrix, Inc.


Date:  October 16, 1998               /s/ Vernon A. Norviel
                                      ------------------------------------------
                                      Vernon A. Norviel
                                      Senior Vice President, General Counsel and
                                      Secretary



                                      EXHIBITS

EXHIBIT      DESCRIPTION
NUMBER
- -------      -----------
 3.3          Summary  of Rights to Purchase Shares of Preferred Stock pursuant
              to the Rights Agreement dated as of October 15, 1998.

EX-3.3

          UNDER CERTAIN CIRCUMSTANCES, AS SET FORTH IN THE RIGHTS
          AGREEMENT, RIGHTS OWNED BY OR TRANSFERRED TO ANY PERSON WHO
          IS OR BECOMES AN ACQUIRING PERSON (AS DEFINED IN THE RIGHTS
          AGREEMENT) AND CERTAIN TRANSFEREES THEREOF WILL BECOME NULL
          AND VOID AND WILL NO LONGER BE TRANSFERABLE.


                           SUMMARY OF RIGHTS TO PURCHASE
                            SHARES OF PREFERRED STOCK OF
                                  AFFYMETRIX, INC.

          On October 15, 1998, the Board of Directors of Affymetrix, Inc. (the
"Company") declared a dividend of (i) one preferred share purchase right (a
"Right") for each outstanding share of common stock, par value $.01 per share,
of the Company (the "Common Stock"), and (ii) a number of Rights for each share
of Series AA Preferred Stock, par value $.01 per share, of the Company (the
"Series AA Preferred Stock") equal to the number of shares of Common Stock into
which such share of Series AA Preferred Stock was convertible at the close of
business on the Record Date (as hereinafter defined).  The dividend is payable
on October 27, 1998 (the "Record Date") to the stockholders of record on that
date.  Each Right entitles the registered holder to purchase from the Company
one one-thousandth of a share of Series B Junior Participating Preferred Stock,
par value $.01 per share, of the Company (the "Series B Preferred Stock") at a
price of $125.00 per one one-thousandth of a share of Series B Preferred Stock
(the "Purchase Price"), subject to adjustment.  The description and terms of the
Rights are set forth in a Rights Agreement dated as of October 15, 1998, as the
same may be amended from time to time (the "Rights Agreement"), between the
Company and American Stock Transfer & Trust Company, as Rights Agent (the
"Rights Agent").

          Until the earlier to occur of (i) 10 days following a public
announcement that a person or group of affiliated or associated persons (with
certain exceptions, an "Acquiring Person") has acquired beneficial ownership of
15% or more in aggregate voting power of the outstanding shares of Common Stock
and Series AA Preferred Stock or (ii) 10 business days (or such later date as
may be determined by action of the Board of Directors prior to such time as any
person or group of affiliated persons becomes an Acquiring Person) following the
commencement of, or announcement of an intention to make, a tender offer or
exchange offer the consummation of which would result in the beneficial
ownership by a person or group of 15% or more in aggregate voting power of the
outstanding shares of Common Stock and Series AA Preferred Stock (the earlier of
such dates being called the "Distribution Date"), the Rights will be evidenced,
with respect to any of the Common Stock certificates or Series AA Preferred
Stock certificates outstanding as of the Record Date, by such Common Stock
certificate or Series AA Preferred Stock certificate, in each case together with
a copy of this Summary of Rights.

          The Rights Agreement provides that, until the Distribution Date (or
earlier expiration of the Rights), the Rights will be transferred with and only
with the Common Stock or 



the Series AA Preferred Stock, respectively.  Until the Distribution Date (or 
earlier expiration of the Rights), new Common Stock certificates issued after 
the Record Date upon transfer or new issuances of Common Stock will contain a 
notation incorporating the Rights Agreement by reference.  Until the 
Distribution Date (or earlier expiration of the Rights), the surrender for 
transfer of any certificates for shares of Common Stock or Series AA 
Preferred Stock outstanding as of the Record Date, even without such notation 
or a copy of this Summary of Rights, will also constitute the transfer of the 
Rights associated with the shares of Common Stock or Series AA Preferred 
Stock represented by such certificate.  As soon as practicable following the 
Distribution Date, separate certificates evidencing the Rights ("Right 
Certificates") will be mailed to (i) holders of record of the Common Stock as 
of the close of business on the Distribution Date and (ii) holders of record 
of Series AA Preferred Stock as of the close of business on the Distribution 
Date who hold shares of Series AA Preferred Stock which were outstanding on 
the Record Date.

          The Rights are not exercisable until the Distribution Date.  The
Rights will expire on October 15, 2008 (the "Final Expiration Date"), unless the
Final Expiration Date is advanced or extended or unless the Rights are earlier
redeemed or exchanged by the Company, in each case as described below.

          The Purchase Price payable, and the number of shares of Series B
Preferred Stock or other securities or property issuable, upon exercise of the
Rights is subject to adjustment from time to time to prevent dilution (i) in the
event of a stock dividend on, or a subdivision, combination or reclassification
of, the Series B Preferred Stock, (ii) upon the grant to holders of the Series B
Preferred Stock of certain rights or warrants to subscribe for or purchase
Series B Preferred Stock at a price, or securities convertible into Series B
Preferred Stock with a conversion price, less than the then-current market price
of the Series B Preferred Stock or (iii) upon the distribution to holders of the
Series B Preferred Stock of evidences of indebtedness or assets (excluding
regular periodic cash dividends or dividends payable in Series B Preferred
Stock) or of subscription rights or warrants (other than those referred to
above).

          The number of outstanding Rights is subject to adjustment in the event
of a stock dividend on the Common Stock payable in shares of Common Stock, or
subdivisions, consolidations or combinations of the Common Stock or Series AA
Preferred Stock occurring, in any such case, prior to the Distribution Date.

          Shares of Series B Preferred Stock purchasable upon exercise of the
Rights will not be redeemable.  Each share of Series B Preferred Stock will be
entitled, when, as and if declared, to a minimum preferential quarterly dividend
payment of the greater of (a) $10 per share, and (b) an amount equal to 1000
times the dividend declared per share of Common Stock.  In the event of
liquidation, dissolution or winding up of the Company, the holders of the Series
B Preferred Stock will be entitled to a minimum preferential payment of the
greater of (a) $10 per share (plus any accrued but unpaid dividends), (b) an
amount equal to 1000 times the payment made per share of Common Stock.  Each
share of Series B Preferred Stock will have 1000 votes, voting together with the
Common Stock.  Finally, in the event of any merger, consolidation or other
transaction in which outstanding shares of Common Stock are converted or
exchanged, each share of Series B Preferred Stock will be entitled to receive
1000 times the amount received per share of Common Stock.  These rights are
protected by customary antidilution provisions.



          Because of the nature of the Series B Preferred Stock's dividend,
liquidation and voting rights, the value of the one one-thousandth interest in a
share of Series B Preferred Stock purchasable upon exercise of each Right should
approximate the value of one share of Common Stock.

          In the event that any person or group of affiliated or associated
persons becomes an Acquiring Person, each holder of a Right, other than Rights
beneficially owned by the Acquiring Person (which will thereupon become void),
will thereafter have the right to receive upon exercise of a Right that number
of shares of Common Stock having a market value of two times the exercise price
of the Right.

          In the event that, after a person or group has become an Acquiring
Person, the Company is acquired in a merger or other business combination
transaction or 50% or more of its consolidated assets or earning power are sold,
proper provisions will be made so that each holder of a Right (other than Rights
beneficially owned by an Acquiring Person which will have become void) will
thereafter have the right to receive upon the exercise of a Right that number of
shares of common stock of the person with whom the Company has engaged in the
foregoing transaction (or its parent) that at the time of such transaction have
a market value of two times the exercise price of the Right.

          At any time after any person or group becomes an Acquiring Person and
prior to the earlier of one of the events described in the previous paragraph or
the acquisition by such Acquiring Person of 50% or more in aggregate voting
power of the outstanding shares of Common Stock and Series AA Preferred Stock,
the Board of Directors of the Company may exchange the Rights (other than Rights
owned by such Acquiring Person which will have become void), in whole or in
part, for shares of Common Stock or Series B Preferred Stock (or a series of the
Company's preferred stock having equivalent rights, preferences and privileges),
at an exchange ratio of one share of Common Stock, or a fractional share of
Series B Preferred Stock (or other preferred stock) equivalent in value thereto,
per Right.

          With certain exceptions, no adjustment in the Purchase Price will be
required until cumulative adjustments require an adjustment of at least 1% in
such Purchase Price.  No fractional shares of Series B Preferred Stock or Common
Stock will be issued (other than fractions of Series B Preferred Stock which are
integral multiples of one one-thousandth of a share of Series B Preferred Stock,
which may, at the election of the Company, be evidenced by depositary receipts),
and in lieu thereof an adjustment in cash will be made based on the current
market price of the Series B Preferred Stock or the Common Stock.

          At any time prior to the time an Acquiring Person becomes such, the
Board of Directors of the Company may redeem the Rights in whole, but not in
part, at a price of $.01 per Right (the "Redemption Price") payable, at the
option of the Company, in cash, shares of Common Stock or such other form of
consideration as the Board of Directors of the Company shall determine.  The
redemption of the Rights may be made effective at such time, on such basis and
with such conditions as the Board of Directors in its sole discretion may
establish.  Immediately upon any redemption of the Rights, the right to exercise
the Rights will terminate and the only right of the holders of Rights will be to
receive the Redemption Price.



          For so long as the Rights are then redeemable, the Company may, except
with respect to the Redemption Price, amend the Rights Agreement in any manner. 
After the Rights are no longer redeemable, the Company may, except with respect
to the Redemption Price, amend the Rights Agreement in any manner that does not
adversely affect the interests of holders of the Rights.

          Until a Right is exercised or exchanged, the holder thereof, as such,
will have no rights as a stockholder of the Company, including, without
limitation, the right to vote or to receive dividends.

          A copy of the Rights Agreement has been filed with the Securities and
Exchange Commission as an Exhibit to a Registration Statement on Form 8-A dated
October 16, 1998.  A copy of the Rights Agreement is available free of charge
from the Company.  This summary description of the Rights does not purport to be
complete and is qualified in its entirety by reference to the Rights Agreement,
as the same may be amended from time to time, which is hereby incorporated
herein by reference.