Filed pursuant to Rule 424(b)(3)
                                          File Number 333-57180 and 333-57180-01

PROSPECTUS SUPPLEMENT NO. 4

                                 $3,035,000,000

                         TYCO INTERNATIONAL GROUP S.A.

                  Zero Coupon Convertible Debentures Due 2021
                    Fully and Unconditionally Guaranteed by
         and Convertible into Common Shares of Tyco International Ltd.

   This prospectus supplement supplements the prospectus dated April 2, 2001 of
Tyco International Group S.A. and Tyco International Ltd., as supplemented
April 13, 2001, April 27, 2001 and May 14, 2001, relating to the sale by
certain of our securityholders (including their pledgees, donees, assignees,
transferees, successors and others who later hold any of our securityholders'
interests) of up to $3,035,000,000 aggregate principal amount at maturity of
the debentures and the common shares issuable upon conversion, and/or purchase
by us, of the debentures. You should read this prospectus supplement in
conjunction with the prospectus, and this prospectus supplement is qualified by
reference to the prospectus, except to the extent that the information in this
prospectus supplement supersedes the information contained in the prospectus.
Capitalized terms used in this prospectus supplement and not otherwise defined
herein have the meanings specified in the prospectus.

   The table of Selling Securityholders contained in the prospectus is hereby
amended to add the entities who are named below as selling securityholders.



                            Aggregate
                         Principal Amount               Number of Tyco Percentage of
                          at Maturity of  Percentage of Common Shares   Tyco Common
                         Debentures That   Debentures    That May be       Shares
Name                       May be Sold     Outstanding     Sold(1)     Outstanding(2)
----                     ---------------- ------------- -------------- --------------
                                                           
New York Life Insurance
 Company................   $ 12,300,000         *           106,906          *
New York Life Insurance
 and Annuity
 Corporation............      1,200,000         *            10,429          *

   Additionally, the following represents updated information regarding the
selling securityholders listed in the Selling Securityholder table in the
prospectus:


                            Aggregate
                         Principal Amount               Number of Tyco Percentage of
                          at Maturity of  Percentage of Common Shares   Tyco Common
                         Debentures That   Debentures    That May be       Shares
Name                       May be Sold     Outstanding     Sold(1)     Outstanding(2)
----                     ---------------- ------------- -------------- --------------
                                                           
Goldman Sachs and
 Company................   $ 25,750,000         *           223,808           *
All other holders of
 debentures or future
 transferees, pledgees,
 donees, assignees or
 successors of any such
 holders (3)(4).........   $483,841,000       15.9%       4,205,352           *

-------
 * Less than one percent (1%).

(1) Assumes conversion of all of the holder's debentures at a conversion rate
    of 8.6916 Tyco common shares per $1,000 principal amount at maturity of the
    debentures. This conversion rate is subject to adjustment, however, as
    described under "Description of the Debentures--Conversion Rights--
    Conversion Rate and Delivery of Tyco Common Shares." As a result, the
    number of Tyco common shares issuable upon conversion of the debentures may
    increase or decrease in the future. Does not include Tyco common shares
    that may be issued by us upon purchase of debentures by us at the option of
    the holder.
(2) Calculated based on Rule 13d-3(d)(i) of the Exchange Act, using
    1,753,548,058 Tyco common shares outstanding as of March 2, 2001. In
    calculating this amount for each holder, we treated as outstanding the
    number of Tyco common shares issuable upon conversion of all of that
    holder's debentures, but we did not assume conversion of any other holder's
    debentures. Does not include Tyco common shares that may be issued by us
    upon purchase of debentures by us at the option of the holder.
(3) Information about other selling securityholders will be set forth in
    prospectus supplements, if required.
(4) Assumes that any other holders of the debentures, or any future pledgees,
    donees, assignees, transferees or successors of or from any such other
    holders of the debentures, do not beneficially own any Tyco common shares
    other than the Tyco common shares issuable upon conversion of the
    debentures at the initial conversion rate.

   INVESTING IN THE DEBENTURES INVOLVES RISKS THAT ARE DESCRIBED IN THE "RISK
FACTORS RELATING TO THE DEBENTURES" SECTION BEGINNING ON PAGE 10 OF THE
PROSPECTUS.

   Neither the Securities and Exchange Commission, any state securities
commission nor any other regulatory body has approved or disapproved of these
securities or determined if this prospectus is truthful or complete. Any
representation to the contrary is a criminal offense.

            The date of this prospectus supplement is May 21, 2001.