<PAGE>

     As filed with the Securities and Exchange Commission on July 2, 2001
                                                     Registration No. 333-______

================================================================================

                      SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C. 20549

                                   FORM S-8

                         REGISTRATION STATEMENT UNDER
                          THE SECURITIES ACT OF 1933

                               CYTYC CORPORATION
            (Exact Name of Registrant as Specified in Its Charter)

          Delaware                                       02-0407755
(State or Other Jurisdiction of             (I.R.S. Employer Identification No.)
Incorporation or Organization)

                               Cytyc Corporation
                                85 Swanson Road
                             Boxborough, MA 01719
              (Address of Principal Executive Offices) (Zip Code)

                             ____________________

                     2001 Non-Employee Director Stock Plan
                           (Full Title of the Plan)
                             ____________________

                              Patrick J. Sullivan
                     President and Chief Executive Officer
                               Cytyc Corporation
                                85 Swanson Road
                             Boxborough, MA 01719
                    (Name and Address of Agent For Service)

                                (978) 263-8000
         (Telephone Number, Including Area Code, of Agent For Service)
                             ____________________

                                   Copy to:

                           JONATHAN M. MOULTON, ESQ.
                        TESTA, HURWITZ & THIBEAULT, LLP
                                125 High Street
                          Boston, Massachusetts 02110
                                (617) 248-7000


                        CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
=========================================================================================================================
                                                                    Proposed          Proposed
                                                                     Maximum           Maximum
                                                 Amount to be     Offering Price      Aggregate         Amount of
    Title of Securities to be Registered          Registered         Per Share     Offering Price    Registration Fee
    ------------------------------------          ----------         ---------     --------------    ----------------
<S>                                             <C>               <C>              <C>               <C>
2001 Non-Employee Director Stock Plan           4,000,000(1)      $22.755          $91,020,000.00    $22,755.00
Common Stock (par value $0.01 per share)
</TABLE>
____________________

(1)  None of such shares are subject to outstanding options. The exercise price
     of such options shall be determined at the time of grant. Accordingly,
     pursuant to Rule 457(c) and Rule 457(h), the proposed maximum offering
     price of $22.755 per share, which is the average of the high and low
     prices of the Common Stock of the Company reported on the Nasdaq National
     Market on June 26, 2001, is set forth solely for purposes of calculating
     the filing fee.

================================================================================
<PAGE>

                                    PART I

             INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

Item 1.   Plan Information.

     The documents containing the information specified in this Item 1 will be
sent or given to employees, directors and others as specified by Rule 428(b)(1).
In accordance with the rules and regulations of the Securities and Exchange
Commission (the "Commission") and the instructions to Form S-8, such documents
are not being filed with the Commission either as part of this Registration
Statement or as prospectuses or prospectus supplements pursuant to Rule 424.

Item 2.   Registrant Information and Employee Plan Annual Information.

     The documents containing the information specified in this Item 2 will be
sent or given to employees, directors or others as specified by Rule 428(b)(1).
In accordance with the rules and regulations of the Commission and the
instructions to Form S-8, such documents are not being filed with the Commission
either as part of this Registration Statement or as prospectuses or prospectus
supplements pursuant to Rule 424.

                                    PART II

              INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.   Incorporation of Documents by Reference.

     The following documents filed by Cytyc Corporation (the "Company" or the
"Registrant" ) with the Commission pursuant to the Securities Act of 1933, as
amended (the "Securities Act") and the Securities Exchange Act of 1934, as
amended (the "Exchange Act") are incorporated by reference in this Registration
Statement:

     (a)  The Company's Annual Report on Form 10-K for the fiscal year ended
          December 31, 2000 filed pursuant to the Exchange Act;


     (b)  The Company's Quarterly Report on Form 10-Q for the fiscal quarter
          ended March 31, 2001 filed pursuant to the Exchange Act; and

     (c)  The section entitled "Description of Registrant's Securities to be
          Registered" contained in the Company's Registration Statement on Form
          8-A, filed with the Commission pursuant to Section 12(g) of the
          Exchange Act on January 16, 1996.

     All documents subsequently filed with the Commission by the Company
pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act, prior to
the filing of a post-effective amendment which indicates that all securities
offered herein have been sold or which deregisters all securities then remaining
unsold, shall be deemed to be incorporated by reference in this Registration
Statement and to be a part hereof from the date of filing of such documents.
<PAGE>

     Any statement contained in any document incorporated, or deemed to be
incorporated, by reference herein shall be deemed to be modified or superseded
for purposes of this Registration Statement to the extent that a statement
contained herein or in any subsequently filed document which also is, or is
deemed to be, incorporated by reference herein modifies or supersedes such
statement. Except as so modified or superseded, such statement shall not be
deemed to constitute a part of this Registration Statement.

Item 4.   Description of Securities.

          Not applicable.

Item 5.   Interest of Named Experts and Counsel.

          Not applicable.

Item 6.   Indemnification of Directors and Officers.

     The Delaware General Corporation Law and the Company's Third Amended and
Restated Certificate of Incorporation, as amended, and Amended and Restated By-
Laws provide for indemnification of the Company's directors and officers for
liabilities and expenses that they may incur in such capacities.  In general,
directors and officers are indemnified with respect to actions taken in good
faith in a manner reasonably believed to be in, or not opposed to, the best
interests of the Registrant, and with respect to any criminal action or
proceeding, actions that the indemnitee had no reasonable cause to believe were
unlawful.

     The Company has obtained directors and officers liability insurance for the
benefit of its directors and officers.

Item 7.   Exemption from Registration Claimed.

     Not applicable.
<PAGE>

Item 8.   Exhibits.
          --------

<TABLE>
<CAPTION>
     Exhibit No.                   Description
     -----------                   -----------
     <S>                 <C>
     Exhibit 5(1)        Opinion of Testa, Hurwitz & Thibeault, LLP.

     Exhibit 23.1(1)     Consent of Arthur Andersen LLP.

     Exhibit 23.2(1)     Consent of Testa, Hurwitz & Thibeault, LLP (included in
                         Exhibit 5).

     Exhibit 24.1(1)     Power of Attorney (included as part of the signature
                         page to this Registration Statement).
</TABLE>


     (1)  Filed herewith.
<PAGE>

     Item 9.  Undertakings.

(a)       The undersigned Registrant hereby undertakes:

               (1)  To file, during any period in which offers or sales are
               being made, a post-effective amendment to this Registration
               Statement:

                    (i)  To include any material information with respect to the
                         plan of distribution not previously disclosed in the
                         registration statement or any material change to such
                         information in the registration statement.

               (2)  That, for the purpose of determining any liability under the
               Securities Act of 1933, each such post-effective amendment shall
               be deemed to be a new registration statement relating to the
               securities offered therein, and the offering of such securities
               at that time shall be deemed to be the initial bona fide offering
               thereof;

               (3)  To remove from registration by means of a post-effective
               amendment any of the securities being registered which remain
               unsold at the termination of the offering.

(b)       The undersigned Registrant hereby undertakes that, for purposes of
          determining any liability under the Securities Act of 1933, each
          filing of the Registrant's annual report pursuant to Section 13(a) or
          Section 15(d) of the Securities Exchange Act of 1934 (and, where
          applicable, each filing of an employee benefit plan's annual report
          pursuant to Section 15(d) of the Securities Exchange Act of 1934) that
          is incorporated by reference in the registration statement shall be
          deemed to be a new registration statement relating to the securities
          offered therein, and the offering of such securities at that time
          shall be deemed to be the initial bona fide offering thereof.

(c)       Insofar as indemnification for liabilities arising under the
          Securities Act of 1933 may be permitted to directors, officers and
          controlling persons of the Registrant pursuant to the foregoing
          provisions, or otherwise, the Registrant has been advised that in the
          opinion of the Securities and Exchange Commission such indemnification
          is against public policy as expressed in the Act and is, therefore,
          unenforceable. In the event that a claim for indemnification against
          such liabilities (other than the payment by the Registrant of expenses
          incurred or paid by a director, officer or controlling person of the
          Registrant in the successful defense of any action, suit or
          proceeding) is asserted by such director, officer or controlling
          person in connection with the securities being registered, the
          Registrant will, unless in the opinion of its counsel the matter has
          been settled by controlling precedent, submit to a court of
          appropriate jurisdiction the question whether such indemnification by
          it is against public policy as expressed in the Act and will be
          governed by the final adjudication of such issue.
<PAGE>

                                  SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Boxborough, Commonwealth of Massachusetts, on this
2nd day of July, 2001.

                                   CYTYC CORPORATION

                                   By: /s/ Patrick J. Sullivan
                                       -----------------------
                                       Patrick J. Sullivan
                                       President and Chief Executive Officer

                       POWER OF ATTORNEY AND SIGNATURES

     The undersigned officers and directors of Cytyc Corporation, hereby
constitute and appoint Patrick J. Sullivan and Robert L. Bowen, and each of them
singly, our true and lawful attorneys-in-fact, with full power to them and each
of them singly, to sign for us in our names in the capacities indicated below,
any amendments to this Registration Statement on Form S-8 (including post-
effective amendments), and to file the same, with all exhibits thereto and other
documents in connection therewith, with the Securities and Exchange Commission,
and generally to do all things in our names and on our behalf in our capacities
as officers and directors to enable Cytyc Corporation, to comply with the
provisions of the Securities Act of 1933, as amended, hereby ratifying and
confirming our signatures as they may be signed by our said attorneys, or any of
them, to said Registration Statement and all amendments thereto.

     Pursuant to the requirements of the Securities Act of 1933, this
registration statement has been signed by the following persons in the
capacities indicated below:

<TABLE>
<CAPTION>
                Signature                                      Title(s)                              Date
                ---------                                      --------                              ----
<S>                                        <C>                                                   <C>

/s/ Patrick J. Sullivan                    President, Chief Executive Officer and Vice           July 2, 2001
-----------------------------------------     Chairman of the Board (Principal Executive
Patrick J. Sullivan                           Officer)


/s/ Robert L. Bowen                        Vice President, Chief Financial Officer and           July 2, 2001
-----------------------------------------     Treasurer (Principal Financial and Accounting
Robert L. Bowen                               Officer)


/s/ Sally W. Crawford                      Director                                              July 2, 2001
-----------------------------------------
Sally W. Crawford

/s/ Alfred J. Battaglia                    Director                                              July 2, 2001
-----------------------------------------
Alfred J. Battaglia

/s/ William G. Little                      Director                                              July 2, 2001
-----------------------------------------
William G. Little

/s/ C. William McDaniel                    Vice Chairman of the Board                            July 2, 2001
-----------------------------------------
C. William McDaniel

/s/ Anna S. Richo                          Director                                              July 2, 2001
-----------------------------------------
Anna S. Richo

/s/ Monroe E. Trout, M.D.                  Chairman of the Board                                 July 2, 2001
-----------------------------------------
Monroe E. Trout, M.D.

/s/ Walter E. Boomer                       Director                                              July 2, 2001
-----------------------------------------
Walter E. Boomer

/s/ William H. Longfield                   Director                                              July 2, 2001
-----------------------------------------
William H. Longfield

</TABLE>


<PAGE>

                               INDEX TO EXHIBITS

<TABLE>
<CAPTION>
Exhibit No.                                   Description
-----------                                   -----------
<S>                <C>
Exhibit 5(1)       Opinion of Testa, Hurwitz & Thibeault, LLP.

Exhibit 23.1(1)    Consent of Arthur Andersen LLP.

Exhibit 23.2(1)    Consent of Testa, Hurwitz & Thibeault, LLP (included in
                   Exhibit 5).

Exhibit 24.1(1)    Power of Attorney (included as part of the signature page to
                   this Registration Statement).
</TABLE>

(1)  Filed herewith.
[{"type": "S-8", "sequence": "1", "filename": "ds8.txt", "description": "FORM S-8", "secsgml_size_bytes": 16425}]
{"company-data": {"conformed-name": "CYTYC CORP", "cik": "0000849778", "assigned-sic": "3826", "irs-number": "020407755", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-64362", "film-number": "1673752"}, "business-address": {"street1": "237 CEDAR HILL ST", "city": "MARLBOROUGH", "state": "MA", "zip": "01752", "phone": "5082638000"}, "mail-address": {"street1": "85 SWANSON ROAD", "city": "BOXBOROUGH", "state": "MA", "zip": "01719"}}
As filed with the Securities and Exchange Commission on July 2, 2001
                                                     Registration No. 333-______

================================================================================

                      SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C. 20549

                                   FORM S-8

                         REGISTRATION STATEMENT UNDER
                          THE SECURITIES ACT OF 1933

                               CYTYC CORPORATION
            (Exact Name of Registrant as Specified in Its Charter)

          Delaware                                       02-0407755
(State or Other Jurisdiction of             (I.R.S. Employer Identification No.)
Incorporation or Organization)

                               Cytyc Corporation
                                85 Swanson Road
                             Boxborough, MA 01719
              (Address of Principal Executive Offices) (Zip Code)

                             ____________________

                     2001 Non-Employee Director Stock Plan
                           (Full Title of the Plan)
                             ____________________

                              Patrick J. Sullivan
                     President and Chief Executive Officer
                               Cytyc Corporation
                                85 Swanson Road
                             Boxborough, MA 01719
                    (Name and Address of Agent For Service)

                                (978) 263-8000
         (Telephone Number, Including Area Code, of Agent For Service)
                             ____________________

                                   Copy to:

                           JONATHAN M. MOULTON, ESQ.
                        TESTA, HURWITZ & THIBEAULT, LLP
                                125 High Street
                          Boston, Massachusetts 02110
                                (617) 248-7000

                        CALCULATION OF REGISTRATION FEE
=========================================================================================================================
                                                                    Proposed          Proposed
                                                                     Maximum           Maximum
                                                 Amount to be     Offering Price      Aggregate         Amount of
    Title of Securities to be Registered          Registered         Per Share     Offering Price    Registration Fee
    ------------------------------------          ----------         ---------     --------------    ----------------
2001 Non-Employee Director Stock Plan           4,000,000(1)      $22.755          $91,020,000.00    $22,755.00
Common Stock (par value $0.01 per share)
____________________

(1)  None of such shares are subject to outstanding options. The exercise price
     of such options shall be determined at the time of grant. Accordingly,
     pursuant to Rule 457(c) and Rule 457(h), the proposed maximum offering
     price of $22.755 per share, which is the average of the high and low
     prices of the Common Stock of the Company reported on the Nasdaq National
     Market on June 26, 2001, is set forth solely for purposes of calculating
     the filing fee.

================================================================================
PART I

             INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

Item 1.   Plan Information.

     The documents containing the information specified in this Item 1 will be
sent or given to employees, directors and others as specified by Rule 428(b)(1).
In accordance with the rules and regulations of the Securities and Exchange
Commission (the "Commission") and the instructions to Form S-8, such documents
are not being filed with the Commission either as part of this Registration
Statement or as prospectuses or prospectus supplements pursuant to Rule 424.

Item 2.   Registrant Information and Employee Plan Annual Information.

     The documents containing the information specified in this Item 2 will be
sent or given to employees, directors or others as specified by Rule 428(b)(1).
In accordance with the rules and regulations of the Commission and the
instructions to Form S-8, such documents are not being filed with the Commission
either as part of this Registration Statement or as prospectuses or prospectus
supplements pursuant to Rule 424.

                                    PART II

              INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.   Incorporation of Documents by Reference.

     The following documents filed by Cytyc Corporation (the "Company" or the
"Registrant" ) with the Commission pursuant to the Securities Act of 1933, as
amended (the "Securities Act") and the Securities Exchange Act of 1934, as
amended (the "Exchange Act") are incorporated by reference in this Registration
Statement:

     (a)  The Company's Annual Report on Form 10-K for the fiscal year ended
          December 31, 2000 filed pursuant to the Exchange Act;

     (b)  The Company's Quarterly Report on Form 10-Q for the fiscal quarter
          ended March 31, 2001 filed pursuant to the Exchange Act; and

     (c)  The section entitled "Description of Registrant's Securities to be
          Registered" contained in the Company's Registration Statement on Form
          8-A, filed with the Commission pursuant to Section 12(g) of the
          Exchange Act on January 16, 1996.

     All documents subsequently filed with the Commission by the Company
pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act, prior to
the filing of a post-effective amendment which indicates that all securities
offered herein have been sold or which deregisters all securities then remaining
unsold, shall be deemed to be incorporated by reference in this Registration
Statement and to be a part hereof from the date of filing of such documents.
Any statement contained in any document incorporated, or deemed to be
incorporated, by reference herein shall be deemed to be modified or superseded
for purposes of this Registration Statement to the extent that a statement
contained herein or in any subsequently filed document which also is, or is
deemed to be, incorporated by reference herein modifies or supersedes such
statement. Except as so modified or superseded, such statement shall not be
deemed to constitute a part of this Registration Statement.

Item 4.   Description of Securities.

          Not applicable.

Item 5.   Interest of Named Experts and Counsel.

          Not applicable.

Item 6.   Indemnification of Directors and Officers.

     The Delaware General Corporation Law and the Company's Third Amended and
Restated Certificate of Incorporation, as amended, and Amended and Restated By-
Laws provide for indemnification of the Company's directors and officers for
liabilities and expenses that they may incur in such capacities.  In general,
directors and officers are indemnified with respect to actions taken in good
faith in a manner reasonably believed to be in, or not opposed to, the best
interests of the Registrant, and with respect to any criminal action or
proceeding, actions that the indemnitee had no reasonable cause to believe were
unlawful.

     The Company has obtained directors and officers liability insurance for the
benefit of its directors and officers.

Item 7.   Exemption from Registration Claimed.

     Not applicable.
Item 8.   Exhibits.
          --------
Exhibit No.                   Description
     -----------                   -----------
Exhibit 5(1)        Opinion of Testa, Hurwitz & Thibeault, LLP.

     Exhibit 23.1(1)     Consent of Arthur Andersen LLP.

     Exhibit 23.2(1)     Consent of Testa, Hurwitz & Thibeault, LLP (included in
                         Exhibit 5).

     Exhibit 24.1(1)     Power of Attorney (included as part of the signature
                         page to this Registration Statement).
(1)  Filed herewith.
Item 9.  Undertakings.

(a)       The undersigned Registrant hereby undertakes:

               (1)  To file, during any period in which offers or sales are
               being made, a post-effective amendment to this Registration
               Statement:

                    (i)  To include any material information with respect to the
                         plan of distribution not previously disclosed in the
                         registration statement or any material change to such
                         information in the registration statement.

               (2)  That, for the purpose of determining any liability under the
               Securities Act of 1933, each such post-effective amendment shall
               be deemed to be a new registration statement relating to the
               securities offered therein, and the offering of such securities
               at that time shall be deemed to be the initial bona fide offering
               thereof;

               (3)  To remove from registration by means of a post-effective
               amendment any of the securities being registered which remain
               unsold at the termination of the offering.

(b)       The undersigned Registrant hereby undertakes that, for purposes of
          determining any liability under the Securities Act of 1933, each
          filing of the Registrant's annual report pursuant to Section 13(a) or
          Section 15(d) of the Securities Exchange Act of 1934 (and, where
          applicable, each filing of an employee benefit plan's annual report
          pursuant to Section 15(d) of the Securities Exchange Act of 1934) that
          is incorporated by reference in the registration statement shall be
          deemed to be a new registration statement relating to the securities
          offered therein, and the offering of such securities at that time
          shall be deemed to be the initial bona fide offering thereof.

(c)       Insofar as indemnification for liabilities arising under the
          Securities Act of 1933 may be permitted to directors, officers and
          controlling persons of the Registrant pursuant to the foregoing
          provisions, or otherwise, the Registrant has been advised that in the
          opinion of the Securities and Exchange Commission such indemnification
          is against public policy as expressed in the Act and is, therefore,
          unenforceable. In the event that a claim for indemnification against
          such liabilities (other than the payment by the Registrant of expenses
          incurred or paid by a director, officer or controlling person of the
          Registrant in the successful defense of any action, suit or
          proceeding) is asserted by such director, officer or controlling
          person in connection with the securities being registered, the
          Registrant will, unless in the opinion of its counsel the matter has
          been settled by controlling precedent, submit to a court of
          appropriate jurisdiction the question whether such indemnification by
          it is against public policy as expressed in the Act and will be
          governed by the final adjudication of such issue.
SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Boxborough, Commonwealth of Massachusetts, on this
2nd day of July, 2001.

                                   CYTYC CORPORATION

                                   By: /s/ Patrick J. Sullivan
                                       -----------------------
                                       Patrick J. Sullivan
                                       President and Chief Executive Officer

                       POWER OF ATTORNEY AND SIGNATURES

     The undersigned officers and directors of Cytyc Corporation, hereby
constitute and appoint Patrick J. Sullivan and Robert L. Bowen, and each of them
singly, our true and lawful attorneys-in-fact, with full power to them and each
of them singly, to sign for us in our names in the capacities indicated below,
any amendments to this Registration Statement on Form S-8 (including post-
effective amendments), and to file the same, with all exhibits thereto and other
documents in connection therewith, with the Securities and Exchange Commission,
and generally to do all things in our names and on our behalf in our capacities
as officers and directors to enable Cytyc Corporation, to comply with the
provisions of the Securities Act of 1933, as amended, hereby ratifying and
confirming our signatures as they may be signed by our said attorneys, or any of
them, to said Registration Statement and all amendments thereto.

     Pursuant to the requirements of the Securities Act of 1933, this
registration statement has been signed by the following persons in the
capacities indicated below:
Signature                                      Title(s)                              Date
                ---------                                      --------                              ----
/s/ Patrick J. Sullivan                    President, Chief Executive Officer and Vice           July 2, 2001
-----------------------------------------     Chairman of the Board (Principal Executive
Patrick J. Sullivan                           Officer)

/s/ Robert L. Bowen                        Vice President, Chief Financial Officer and           July 2, 2001
-----------------------------------------     Treasurer (Principal Financial and Accounting
Robert L. Bowen                               Officer)

/s/ Sally W. Crawford                      Director                                              July 2, 2001
-----------------------------------------
Sally W. Crawford

/s/ Alfred J. Battaglia                    Director                                              July 2, 2001
-----------------------------------------
Alfred J. Battaglia

/s/ William G. Little                      Director                                              July 2, 2001
-----------------------------------------
William G. Little

/s/ C. William McDaniel                    Vice Chairman of the Board                            July 2, 2001
-----------------------------------------
C. William McDaniel

/s/ Anna S. Richo                          Director                                              July 2, 2001
-----------------------------------------
Anna S. Richo

/s/ Monroe E. Trout, M.D.                  Chairman of the Board                                 July 2, 2001
-----------------------------------------
Monroe E. Trout, M.D.

/s/ Walter E. Boomer                       Director                                              July 2, 2001
-----------------------------------------
Walter E. Boomer

/s/ William H. Longfield                   Director                                              July 2, 2001
-----------------------------------------
William H. Longfield
INDEX TO EXHIBITS
Exhibit No.                                   Description
-----------                                   -----------
Exhibit 5(1)       Opinion of Testa, Hurwitz & Thibeault, LLP.

Exhibit 23.1(1)    Consent of Arthur Andersen LLP.

Exhibit 23.2(1)    Consent of Testa, Hurwitz & Thibeault, LLP (included in
                   Exhibit 5).

Exhibit 24.1(1)    Power of Attorney (included as part of the signature page to
                   this Registration Statement).
(1)  Filed herewith.