Exhibit 5

                              May 21, 1999


Hologic, Inc.
35 Crosby Drive
Bedford, MA 01730-1401

RE:  Registration Statement on Form S-8

Ladies and Gentlemen:

     We are general counsel to Hologic, Inc., a Delaware
corporation (the "Company").  We have been asked to deliver this
opinion in connection with the preparation and filing with the
Securities and Exchange Commission under the Securities Act of
1933, as amended (the "Act"), of a Registration Statement on Form
S-8 (the "Registration Statement") relating to (i) 1,600,000
shares of the Company's Common Stock, $.01 par value (the
"Shares"), 1,500,000 of which may be issued pursuant to options
granted under the Company's Amended and Restated 1999 Equity
Incentive Plan (the "1999 Plan") and 100,000 of which may be
issued pursuant to options granted under the Company's 1997
Employee Equity Incentive Plan (the "1997 Plan"); and (ii)
1,600,000 Rights (as defined below) that may be issued in
connection with the issuance of the Shares pursuant to options
granted under such plans.  The Rights are issuable pursuant to
that certain Rights Agreement, dated as of December 22, 1992, as
amended by Amendment No. 1, dated December 14, 1995, Amendment
No. 2, dated as of December 9, 1996, and Amendment No. 3, dated
as of April 25, 1999 (the "Rights Agreement"), providing, in
effect, for the delivery of a right (a "Right"), along with each
share of Common Stock issued by the Company.

     In connection with this opinion, we have examined and are
familiar with originals or copies, certified or otherwise
identified to our satisfaction, of the following documents
(collectively, the "Documents"):

     1.   A copy of the Certificate of Incorporation of the Company as
       in effect on the date hereof;

     2.   A copy of the Bylaws of the Company as in effect on the date
       hereof;

     3.   The corporate records of the Company relating to the
       proceedings of stockholders and directors of the Company;

     4.   The 1999 Plan and the 1997 Plan (collectively, the "Plans");

     5.   The Rights Agreement; and

     6.   The Registration Statement.

     In giving our opinion, we have relied as to matters of fact
upon certificates of officers of the Company.  For purposes of
this opinion we have assumed without any investigation (1) the
legal capacity of each natural person and (2) the genuineness of
each signature, the completeness of each document submitted to us
as an original and the conformity with the original of each
document submitted to us as a copy.

     Our opinion hereafter expressed is based solely upon (1) our
review of the Documents, (2) discussions with certain officers of
the Company with respect to the Documents, (3) discussions with
those of our attorneys who have devoted substantive attention to
the matters contained herein and (4) such review of published
sources of law as we have deemed necessary.

   Based upon and subject to the foregoing, we are of the opinion
that  the  Shares have been duly authorized and, when  issued  in
accordance  with  the  terms of the Plans,  the  Shares  will  be
validly  issued, fully paid and nonassessable.  The  Rights  have
been  duly  authorized and, when issued in  accordance  with  the
terms of the Rights Agreement, will be validly issued, fully paid
and nonassessable.

     We hereby consent to the filing of this opinion as Exhibit 5
to the Registration Statement and to the reference to our firm
wherever it appears in the Registration Statement.

                              Very truly yours,

                              BROWN, RUDNICK, FREED & GESMER
                              By:  Brown, Rudnick, Freed &
                              Gesmer, P.C., a partner

                              By: /s/ Philip J. Flink
                                  ---------------------
                                    Philip J. Flink, a Member
                                    hereunto duly authorized