SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

                   -------------------------------------------


                                    FORM 8-K


                                 CURRENT REPORT

                       Pursuant to Section 13 or 15(d) of
                       the Securities Exchange Act of 1934



                                 Date of Report
                       (Date of earliest event reported):

                                   May 3, 1999

                    ----------------------------------------


                             THERMOTREX CORPORATION
             (Exact name of Registrant as specified in its charter)


Delaware                        1-10791                   52-1711436
(State or other               (Commission              (I.R.S. Employer
jurisdiction of               File Number)             Identification Number)
incorporation or
organization)


10455 Pacific Center Court
San Diego, California                                         92121
 (Address of principal executive offices)                   (Zip Code)


                                 (619) 646-5300
                         (Registrant's telephone number
                              including area code)



<PAGE>

     This Form 8-K contains forward-looking  statements that involve a number of
risks and  uncertainties.  Important  factors that could cause actual results to
differ  materially from those indicated by such  forward-looking  statements are
set forth  under the  heading  "Forward-looking  Statements"  in  Exhibit  13 to
ThermoTrex  Corporation's  Annual Report on Form 10-K for the year ended October
3,  1998,  as  amended.  These  include  risks and  uncertainties  relating  to:
development  and   commercialization  of  products  under  development,   market
acceptance,   difficulty  in  retaining   qualified   management  and  
personnel, dependence on capital  spending  policies,  government  contracts,  
decreases in military weapons spending,  compliance with government regulations,
the need for regulatory approvals, healthcare reform and uncertainty of patient 
reimbursement, intense competition, dependence on patents and proprietary 
rights, dependence on significant  relationships,  potential product liability,
risks associated with acquisition  strategy,  and the potential  impact of the 
year 2000 on processing date-sensitive information.

Item 5.     Other Events

      On May 3, 1999, the Registrant issued a press release  announcing that its
majority-owned  subsidiary Trex Medical Corporation ("Trex Medical") will record
pretax  restructuring  and other  charges  totaling  approximately  $11 million.
Approximately  $6 million to $7 million will be recorded in Trex Medical's third
fiscal quarter,  which ends July 3, 1999,  with the remainder  recorded as costs
are incurred over the next several quarters. The majority of the charges will be
incurred  as a  result  of Trex  Medical's  decision  to  close  two of its four
domestic manufacturing  facilities after relocating these operations,  and, to a
lesser extent, as a result of actions to reduce costs in other operations.  This
process  will result in a staff  reduction  of  approximately  15 percent.  Trex
Medical  estimates  that these  actions  will  result in fiscal  2000  operating
savings of approximately $4 million to $5 million.

      Trex Medical's Bennett facility in Copiague, New York, and its Continental
facility in Broadview, Illinois, will be closed. Sales and marketing offices for
Bennett and  Continental  will remain in these  communities.  Manufacturing  and
product   development  of  Trex  Medical's   mammography  systems  will  now  be
concentrated at Trex Medical's Danbury, Connecticut, site. All manufacturing and
product  development of general-purpose and other specialized X-ray systems will
now be conducted at Trex  Medical's  Littleton,  Massachusetts,  facility.  Trex
Medical will continue to  manufacture  its complete  product line and market its
systems under its four existing product line names: Lorad, Bennett, Continental,
and XRE. Distribution channels will be maintained as before.
<PAGE>


Item 7.     Financial Statements, Pro Forma Financial Information and Exhibits

      (a)    Financial Statements of Business Acquired: not
            applicable.

      (b)   Pro Forma Financial Information: not applicable.

      (c)   Exhibits: not applicable.

<PAGE>

                                    SIGNATURE


      Pursuant to the  requirements of the Securities  Exchange Act of 1934, the
Registrant  has duly  caused  this  report  to be  signed  on its  behalf by the
undersigned, thereunto duly authorized, on this 6th day of May, 1999.



                                        THERMOTREX CORPORATION


                                        By:  /s/ Theo Melas-Kyriazi
                                             Theo Melas-Kyriazi
                                             Chief Financial Officer
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SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

                   -------------------------------------------

                                    FORM 8-K

                                 CURRENT REPORT

                       Pursuant to Section 13 or 15(d) of
                       the Securities Exchange Act of 1934

                                 Date of Report
                       (Date of earliest event reported):

                                   May 3, 1999

                    ----------------------------------------

                             THERMOTREX CORPORATION
             (Exact name of Registrant as specified in its charter)

Delaware                        1-10791                   52-1711436
(State or other               (Commission              (I.R.S. Employer
jurisdiction of               File Number)             Identification Number)
incorporation or
organization)

10455 Pacific Center Court
San Diego, California                                         92121
 (Address of principal executive offices)                   (Zip Code)

                                 (619) 646-5300
                         (Registrant's telephone number
                              including area code)
This Form 8-K contains forward-looking  statements that involve a number of
risks and  uncertainties.  Important  factors that could cause actual results to
differ  materially from those indicated by such  forward-looking  statements are
set forth  under the  heading  "Forward-looking  Statements"  in  Exhibit  13 to
ThermoTrex  Corporation's  Annual Report on Form 10-K for the year ended October
3,  1998,  as  amended.  These  include  risks and  uncertainties  relating  to:
development  and   commercialization  of  products  under  development,   market
acceptance,   difficulty  in  retaining   qualified   management  and  
personnel, dependence on capital  spending  policies,  government  contracts,  
decreases in military weapons spending,  compliance with government regulations,
the need for regulatory approvals, healthcare reform and uncertainty of patient 
reimbursement, intense competition, dependence on patents and proprietary 
rights, dependence on significant  relationships,  potential product liability,
risks associated with acquisition  strategy,  and the potential  impact of the 
year 2000 on processing date-sensitive information.

Item 5.     Other Events

      On May 3, 1999, the Registrant issued a press release  announcing that its
majority-owned  subsidiary Trex Medical Corporation ("Trex Medical") will record
pretax  restructuring  and other  charges  totaling  approximately  $11 million.
Approximately  $6 million to $7 million will be recorded in Trex Medical's third
fiscal quarter,  which ends July 3, 1999,  with the remainder  recorded as costs
are incurred over the next several quarters. The majority of the charges will be
incurred  as a  result  of Trex  Medical's  decision  to  close  two of its four
domestic manufacturing  facilities after relocating these operations,  and, to a
lesser extent, as a result of actions to reduce costs in other operations.  This
process  will result in a staff  reduction  of  approximately  15 percent.  Trex
Medical  estimates  that these  actions  will  result in fiscal  2000  operating
savings of approximately $4 million to $5 million.

      Trex Medical's Bennett facility in Copiague, New York, and its Continental
facility in Broadview, Illinois, will be closed. Sales and marketing offices for
Bennett and  Continental  will remain in these  communities.  Manufacturing  and
product   development  of  Trex  Medical's   mammography  systems  will  now  be
concentrated at Trex Medical's Danbury, Connecticut, site. All manufacturing and
product  development of general-purpose and other specialized X-ray systems will
now be conducted at Trex  Medical's  Littleton,  Massachusetts,  facility.  Trex
Medical will continue to  manufacture  its complete  product line and market its
systems under its four existing product line names: Lorad, Bennett, Continental,
and XRE. Distribution channels will be maintained as before.
Item 7.     Financial Statements, Pro Forma Financial Information and Exhibits

      (a)    Financial Statements of Business Acquired: not
            applicable.

      (b)   Pro Forma Financial Information: not applicable.

      (c)   Exhibits: not applicable.
SIGNATURE

      Pursuant to the  requirements of the Securities  Exchange Act of 1934, the
Registrant  has duly  caused  this  report  to be  signed  on its  behalf by the
undersigned, thereunto duly authorized, on this 6th day of May, 1999.

                                        THERMOTREX CORPORATION

                                        By:  /s/ Theo Melas-Kyriazi
                                             Theo Melas-Kyriazi
                                             Chief Financial Officer