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                               AMENDMENT NO. 1 TO

                        PREFERRED STOCK RIGHTS AGREEMENT

                  This Amendment No. 1 dated as of February 18, 2003 (this
"Amendment") to the to Preferred Stock Rights Agreement dated as of October 24,
2001 (the "Rights Agreement") between Third Wave Technologies, Inc., a Delaware
corporation (the "Company"), and EquiServe Trust Company N.A., a national
banking association (the "Rights Agent").

                  WHEREAS, the Board of Directors of the Company, at a meeting
held on December 13, 2002 has determined that it is advisable and in the best
interest of the Company to amend the Rights Agreement between the Company and
the Rights Agent as set forth below;

                  WHEREAS, at the date of this Amendment, a Distribution Date
has not occurred and there is no Acquiring Person; and

                  WHEREAS, in compliance with Section 27 of the Rights
Agreement, the Company and the Rights Agent are willing to amend the Rights
Agreement as hereinafter set forth and the Company and the Rights Agent have
each executed and delivered this Amendment.

                  NOW, THEREFORE, in consideration of the Rights Agreement and
the premises and mutual agreements herein set forth, the parties hereto agree as
follows:

                  SECTION 1. AMENDMENT OF SECTION 1(A) OF THE RIGHTS AGREEMENT.
(a) Section 1(a) of the Rights Agreement is hereby amended to read in its
entirety as follows:

                           "(a) "ACQUIRING PERSON" shall mean (i) any Person,
         other than the State of Wisconsin Investment Board ("SWIB"), who or
         which, together with all Affiliates and Associates of such Person,
         shall be the Beneficial Owner of 15% or more of the Common Shares then
         outstanding, or (ii) SWIB on such date as it, together with all of its
         Affiliates and Associates, shall be the Beneficial Owner of 16.5% or
         more of the Common Shares then outstanding, but shall not include the
         Company, any Subsidiary of the Company or any employee benefit plan of
         the Company or of any Subsidiary of the Company, or any entity holding
         Common Shares for or pursuant to the terms of any such plan.
         Notwithstanding the foregoing, no Person shall be deemed to be an
         Acquiring Person as the result of an acquisition of Common Shares by
         the Company which, by reducing the number of shares outstanding,
         increases the proportionate number of shares beneficially owned by such
         Person to 15% or more (16.5% or more in the case of SWIB) of the Common
         Shares of the Company then outstanding; provided, however, that if a
         Person shall become the Beneficial Owner of 15% or more (16.5% or more
         in the case of SWIB) of the Common Shares of the Company then
         outstanding by reason of share purchases by the Company and shall,
         after such share purchases by the Company, become the Beneficial Owner
         of any additional Common Shares of the Company (other than pursuant to
         a dividend or distribution paid or made by the Company on the
         outstanding Common Shares in Common Shares or pursuant to a split or
         subdivision of the outstanding Common Shares), then such Person shall
         be deemed to be an Acquiring Person unless upon becoming the Beneficial
         Owner of such additional Common Shares of the Company





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         such Person does not beneficially own 15% or more (16.5% or more in the
         case of SWIB) of the Common Shares of the Company then outstanding.
         Notwithstanding the foregoing, (i) if the Company's Board of Directors
         determines in good faith that a Person who would otherwise be an
         "Acquiring Person," as defined pursuant to the foregoing provisions of
         this paragraph (a), has become such inadvertently (including, without
         limitation, because (A) such Person was unaware that it beneficially
         owned a percentage of the Common Shares that would otherwise cause such
         Person to be an "Acquiring Person, " as defined pursuant to the
         foregoing provisions of this paragraph (a), or (B) such Person was
         aware of the extent of the Common Shares it beneficially owned but had
         no actual knowledge of the consequences of such beneficial ownership
         under this Agreement) and without any intention of changing or
         influencing control of the Company, and if such Person divested or
         divests as promptly as practicable a sufficient number of Common Shares
         so that such Person would no longer be an "Acquiring Person," as
         defined pursuant to the foregoing provisions of this paragraph (a),
         then such Person shall not be deemed to be or to have become an
         "Acquiring Person" for any purposes of this Agreement; and (ii) if, as
         of the date hereof, any Person is the Beneficial Owner of 15% or more
         of the Common Shares outstanding, such Person shall not be or become an
         "Acquiring Person," as defined pursuant to the foregoing provisions of
         this paragraph (a), unless and until such time as such Person shall
         become the Beneficial Owner of additional Common Shares (other than
         pursuant to a dividend or distribution paid or made by the Company on
         the outstanding Common Shares in Common Shares or pursuant to a split
         or subdivision of the outstanding Common Shares), unless, upon becoming
         the Beneficial Owner of such additional Common Shares, such Person is
         not then the Beneficial Owner of 15% or more of the Common Shares then
         outstanding."

                  SECTION 2. AMENDMENT OF SECTION 3(C) OF THE RIGHTS AGREEMENT.
Section 3(c) of the Rights Agreement is hereby amended to add the words "AS
AMENDED AS OF FEBRUARY 18, 2003" after the words "RIGHTS AGREEMENT DATED AS OF
OCTOBER 24, 2001".

                  SECTION 3. AMENDMENT OF SECTION 21 OF THE RIGHTS AGREEMENT.
Section 21 of the Rights Agreement is hereby amended by adding thereto, after
the end of the first sentence of Section 21, the following: "If the Rights Agent
shall no longer serve as the transfer agent for the Common Shares, the Rights
Agent shall be deemed to have resigned as such effective as of the date on which
the Rights Agent no longer serves as such transfer agent."

                  SECTION 4. AMENDMENT OF SECTION 26 OF THE RIGHTS AGREEMENT.
Section 26 of the Rights Agreement is hereby amended (a) to change the
Attention: line under the address to which notices or demands to be given to the
Rights Agent must be sent to "Client Administration" and (b) to change the firm
and address to which copies of notices or demands to be given to the Company
must be sent to:


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                  Sidley Austin Brown & Wood
                  Bank One Plaza
                  10 S. Dearborn Street
                  Chicago, Illinois  60603
                  Attention:  Steven Sutherland

                  SECTION 5. AMENDMENT TO ADD SECTION 35 TO THE RIGHTS
AGREEMENT. The Rights Agreement is further amended to add a new Section 35 to
the Rights Agreement, such Section to read in its entirety as follows:

                  "SECTION 35. FORCE MAJEURE. Notwithstanding anything to the
         contrary contained herein, neither the Company nor the Rights Agent
         shall be liable for any delays or failures in performance resulting
         from acts beyond its reasonable control including, without limitation,
         acts of God, terrorist acts, shortage of supply, breakdowns or
         malfunctions, interruptions or malfunction of computer facilities, or
         loss of data due to power failures or mechanical difficulties with
         information storage or retrieval systems, labor difficulties, war or
         civil unrest."

                  SECTION 6. AMENDMENT OF FORM OF RIGHTS CERTIFICATE. The first
paragraph of the form of Rights Certificate attached to the Rights Agreement as
Exhibit B is hereby amended to add the words "as amended as of February 18,
2003" after the words "Rights Agreement dated as of October 24, 2001,".

                  SECTION 7. AMENDMENT OF SUMMARY OF RIGHTS. (a) The paragraph
opposite the caption "Distribution Date:" in the Summary of Rights attached to
the Rights Agreement as Exhibit C is hereby amended to read in its entirety as
follows;

                  "Rights will separate from the Common Stock and become
         exercisable following (a) the tenth day (or such later date as may be
         determined by a majority of the Directors) after a person or group
         acquires beneficial ownership of 15% or more (16.5% or more in the case
         of the State of Wisconsin Investment Board ("SWIB")) of the Company's
         Common Stock or (b) the tenth business day (or such later date as may
         be determined by a majority of the Directors) after a person or group
         announces a tender or exchange offer, the consummation of which would
         result in ownership by a person or group of 15% or more (16.5% or more
         in the case of SWIB) of the Company's Common Stock. "

                  (b) The Summary of Rights is further amended to add the
parenthetical "(16.5% in the case of SWIB)" after each reference to "15% or
more" in each of the paragraphs opposite the captions "Flip-In:", "Exchange
Provision:" and "Redemption of the Rights:".

                  SECTION 8.  INTERPRETATION.

                  (a) Unless otherwise defined herein, capitalized terms used
herein shall have the meanings given to such terms in the Rights Agreement.


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                  (b) Except as otherwise expressly set forth herein, this
Amendment shall not by implication or otherwise alter, modify or in any other
manner affect any of the terms, conditions, obligations, covenants or agreements
contained in the Rights Agreement, all of which are hereby ratified and
confirmed in all respects and shall continue in full force and effect.

                  (c) Section headings in this Amendment are included herein for
convenience of reference only and shall not constitute part of this Amendment
for any other purpose.

                  SECTION 9. EXECUTION IN COUNTERPARTS. This Amendment may be
executed in any number of counterparts, each of which when so executed and
delivered shall be deemed to be an original and all of which taken together
shall constitute one and the same instrument.

                  SECTION 10. GOVERNING LAW. This Amendment shall be deemed to
be a contract made under the laws of the State of Delaware and for all purposes
shall be governed by and construed in accordance with the laws of such State
applicable to contracts to be made and performed entirely within such State.



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                  IN WITNESS WHEREOF, the parties hereto have executed and
delivered this Amendment as of the date first above written.

                                      THIRD WAVE TECHNOLOGIES, INC.


                                      By:  /s/ John Comerford
                                      Name:    John Comerford
                                      Title:   Vice President, General Counsel &
                                               Secretary


                                      EQUISERVE TRUST COMPANY N.A.


                                      By:________________________________
                                          Name:
                                          Title: