SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549

                              --------------------

                                    FORM 8-A
                FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES
                     PURSUANT TO SECTION 12(b) OR (g) OF THE
                         SECURITIES EXCHANGE ACT OF 1934

                                TheraSense, Inc.
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               (Exact name of Registrant as Specified in Charter)

                      Delaware                                   94-3267373
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      (State of Incorporation or Organization)                 (IRS Employer
                                                             Identification No.)

       1360 South Loop Road, Alameda, California                   94502
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        (Address of Principal Executive Offices)                 (Zip Code)

      If this form relates to the             If this form relates to the
      registration of a class of              registration of a class of
      securities pursuant to Section          securities pursuant to Section
      12(b) of the Exchange Act and is        12(g) of the Exchange Act and is
      effective pursuant to General           effective pursuant to General
      Instruction A.(c), please check         Instruction A.(d), please check
      the following box. [ ]                 the following box. [X]

Securities Act registration statement file number to which this form
relates:
        ------------------------
            (If applicable)

Securities to be registered pursuant to Section 12(b) of the Act:

        Title of Each Class                  Name of Each Exchange on Which
        to be so Registered                  Each Class is to be Registered
    -----------------------------            ------------------------------

                None                                      None
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Securities to be registered pursuant to Section 12(g) of the Act:

                         Preferred Stock Purchase Rights
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                                (Title of Class)
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                                (Title of Class)
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Item 1.  Description of Registrant's Securities to be Registered.

     On February 25, 2003, the Board of Directors of TheraSense, Inc. (the
"Company") declared a dividend of one preferred stock purchase right (each, a
"Right" and together, the "Rights") for each outstanding share of common stock,
par value $.001 per share (the "Common Stock"), of the Company payable to
holders of record as of the close of business on March 14, 2003 (the "Record
Date").

     Prior to the Distribution Date (as defined below), the Rights will be
evidenced by the certificates for and will be transferred with the Common Stock,
and the registered holders of the Common Stock will be deemed to be the
registered holders of the Rights. After the Distribution Date, the Rights Agent
will mail separate certificates evidencing the Rights to each record holder of
the Common Stock as of the close of business on the Distribution Date, and
thereafter the Rights will be transferable separately from the Common Stock. The
"Distribution Date" generally means the earlier of (i) the close of business on
the 10th day after the date (the "Stock Acquisition Date") of the first public
announcement that a person (other than the Company or any of its subsidiaries or
any employee benefit plan of the Company or any such subsidiary) has acquired
beneficial ownership of 15% or more of the outstanding shares of Common Stock
(an "Acquiring Person") and (ii) the close of business on the 10th business day
(or such later day as may be designated by the Board of Directors before any
person has become an Acquiring Person) after the date of the commencement of a
tender or exchange offer by any person which would, if consummated, result in
such person becoming an Acquiring Person.

     Prior to the Distribution Date, the Rights will not be exercisable. After
the Distribution Date (but before any person has become an Acquiring Person),
each Right will be exercisable to purchase, for $100.00 (the "Purchase Price"),
one one-thousandth of a share of Series A Participating Cumulative Preferred
Stock, par value $.001 per share (the "Preferred Stock"). The terms and
conditions of the Rights are set forth in a Rights Agreement dated as of March
7, 2003 between the Company and Computershare Investor Services, as Rights Agent
(the "Rights Agreement"), a copy of which is attached as an exhibit hereto and
the description hereof is qualified in its entirety by reference thereto.

     If any person has become an Acquiring Person (but none of the events
described in the second succeeding paragraph has occurred), each Right (other
than Rights beneficially owned by the Acquiring Person and certain affiliated
persons) will entitle the holder, after the Distribution Date, to purchase, for
the Purchase Price, a number of shares of Common Stock having a market value of
twice the Purchase Price.


                                  Page 2 of 5



     At any time after any person has become an Acquiring Person (but before any
person becomes the beneficial owner of 50% or more of the outstanding shares of
Common Stock or the occurrence of any of the events described in the next
paragraph), the Board of Directors may exchange all or part of the Rights (other
than Rights beneficially owned by an Acquiring Person and certain affiliated
persons) for shares of Common Stock at an exchange ratio of one share of Common
Stock per Right.

     If, after any person has become an Acquiring Person, (1) the Company is
involved in a merger or other business combination in which the Company is not
the surviving corporation or its Common Stock is exchanged for other securities
or assets or (2) the Company and/or one or more of its subsidiaries sell or
otherwise transfer assets or earning power aggregating more than 50% of the
assets or earning power of the Company and its subsidiaries, taken as a whole,
then each Right will entitle the holder, after the Distribution Date, to
purchase, for the Purchase Price, a number of shares of common stock of the
other party to such business combination or sale (or in certain circumstances,
an affiliate) having a market value of twice the Purchase Price.

     The Board of Directors may redeem all of the Rights at a price of $0.001
per Right at any time before any person has become an Acquiring Person.

     The Rights will expire on February 25, 2013, unless earlier exchanged or
redeemed.

     For so long as the Rights are redeemable, the Rights Agreement may be
amended in any respect. At any time when the Rights are no longer redeemable,
the Rights Agreement may be amended in any respect that does not adversely
affect Rights holders (other than any Acquiring Person and certain affiliated
persons), cause the Rights Agreement to become amendable except as set forth in
this sentence or cause the Rights again to become redeemable.

     Rights holders have no rights as stockholders of the Company by virtue of
holding the Rights, including the right to vote and to receive dividends.

     The Rights Agreement includes antidilution provisions designed to prevent
efforts to diminish the effectiveness of the Rights.

     As of February 1, 2003 there were 40,818,522 shares of Common Stock
outstanding and 7,380,592 shares of Common Stock reserved for issuance under
the Company's stock option and stock purchase plans. Each outstanding share of
Common Stock on the Record Date will receive one Right. Shares of Common Stock
issued after the Record Date and prior to the Distribution Date will be


                                  Page 3 of 5


issued with a Right attached so that all shares of Common Stock outstanding
prior to the Distribution Date will have Rights attached. 200,000 shares of
Preferred Stock have been reserved for issuance upon exercise of the Rights.

     The Rights have certain anti-takeover effects. The Rights may cause
substantial dilution to a person that attempts to acquire the Company without a
condition to such an offer that a substantial number of the Rights be acquired
or that the Rights be redeemed or declared invalid. The Rights should not
interfere with any merger or other business combination approved by the Board of
Directors since the Rights may be redeemed by the Company as described above.

     While the dividend of the Rights will not be taxable to stockholders or to
the Company, stockholders or the Company may, depending upon the circumstances,
recognize taxable income in the event that the Rights become exercisable as set
forth above.

     The foregoing description of the Rights Agreement is qualified in its
entirety by reference to the full text of the Rights Agreement, which is
attached hereto as Exhibit 1 and incorporated herein by reference.

Item 2.  Exhibits

1.   Rights Agreement dated as of March 7, 2003 between TheraSense, Inc. and
     Computershare Investor Services, as Rights Agent, which includes the Form
     of Certificate of Designation of Series A Participating Cumulative
     Preferred Stock as Exhibit A, the Summary of Terms of the Rights Agreement
     as Exhibit B and the Form of Right Certificate as Exhibit C.


                                  Page 4 of 5



                                    SIGNATURE


     Pursuant to the requirements of Section 12 of the Securities Exchange Act
of 1934, the registrant has duly caused this registration statement to be signed
on its behalf by the undersigned, thereto duly authorized.


                                              TheraSense, Inc.


                                              By: /s/ W. Mark Lortz
                                                  ------------------------------
                                                  Name:  W. Mark Lortz
                                                  Title: Chairman, President and
                                                         Chief Executive Officer

Dated: March 10, 2003




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