<Page>

                                                                     EXHIBIT 4.4

                          AMENDMENT TO RIGHTS AGREEMENT

1.   GENERAL BACKGROUND. In accordance with Section 27 of the Rights Agreement
     between BANKBOSTON, N.A. (the "Rights Agent") and CYTYC CORPORATION (THE
     "COMPANY") dated 8/27/97 (the "Rights Agreement"), the Rights Agent and
     Cytyc Corporation desire to amend the Agreement to appoint EquiServe Trust
     Company, N.A.

2.   EFFECTIVENESS. This Amendment shall be effective as of January 3, 2003 (the
     "Amendment") and all defined terms and definitions in the Agreement shall
     be the same in the Amendment except as specifically revised by the
     Amendment.

3.   REVISION. The section in the Agreement entitled "Change of Rights Agent" is
     hereby deleted in its entirety and replaced with the following:

     CHANGE OF RIGHTS AGENT. The Rights Agent or any successor Rights Agent may
     resign and be discharged from its duties under this Agreement upon 30 days'
     notice in writing mailed to the Company and to each transfer agent of the
     Common Stock and Preferred Stock by registered or certified mail and to the
     holders of the Right Certificates by first-class mail. The Company may
     remove the Rights Agent or any successor Rights Agent upon thirty (30)
     days' notice in writing mailed to the Rights Agent or successor Rights
     Agent, as the case may be, and to each transfer agent of the Common Stock
     and Preferred Stock by registered or certified mail, and to the holders of
     the Right Certificates by first-class mail. If the Rights Agent shall
     resign or be removed or shall otherwise become incapable of acting, the
     Company shall appoint a successor to the Rights Agent. If the Company shall
     fail to make such appointment within a period of thirty (30) days after
     giving notice of such removal or after it has been notified in writing of
     such resignation or incapacity by the resigning or incapacitated Rights
     Agent or by any registered holder of a Right Certificate (who shall, with
     such notice, submit his Rights Certificate for inspection by the Company),
     then any registered holder of any Right Certificate may apply to any court
     of competent jurisdiction for the appointment of a new Rights Agent. Any
     successor Rights Agent, whether appointed by the Company or by such a
     court, shall be a corporation or trust company organized and doing business
     under the laws of the United States or any state thereof, in good standing,
     which is authorized under such laws to exercise corporate trust or stock
     transfer powers and is subject to supervision or examination by federal or
     state authority and which has individually or combined with an affiliate at
     the time its appointment as Rights Agent a combined capital and surplus of
     at least $50 million dollars or (b) an affiliate of a corporation described
     in clause (a) of this sentence. After appointment, the successor Rights
     Agent shall be vested with the same powers, rights, duties and
     responsibilities as

<Page>

     if it had been originally named as Rights Agent without further act or
     deed; but the predecessor Rights Agent shall deliver and transfer to the
     successor Rights Agent any property at the time held by it hereunder, and
     execute and deliver any further assurance, conveyance, act or deed
     necessary for the purpose. Not later than the effective date of any such
     appointment the Company shall file notice thereof in writing with the
     predecessor Rights Agent and each transfer agent of the Common Stock and or
     Preferred Stock, and mail a notice thereof in writing to the registered
     holders of the Right Certificates. Failure to give any notice provided for
     in this Section 21, however, or any defect therein, shall not affect the
     legality or validity of the resignation or removal of the Rights Agent or
     the appointment of the successor Rights Agent, as the case may be.

4.   Except as amended hereby, the Agreement and all schedules or exhibits
     thereto shall remain in full force and effect.

IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed
in their names and on their behalf by and through their duly authorized
officers, as of this third day of January, 2003.

CYTYC CORPORATION                               BANKBOSTON, N.A.


/s/ A. Suzanne Meszner-Eltrich                  /s/ Dennis V. Moccia
---------------------------------------         --------------------------------
A. Suzanne Meszner-Eltrich                      By: Dennis V. Moccia
Vice President, General Counsel                 Title: Managing Director
and Secretary


                                                EQUISERVE TRUST COMPANY, N.A.


                                                /s/ Dennis V. Moccia
                                                --------------------------------
                                                By: Dennis V. Moccia
                                                Title: Managing Director