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):

                                 March 30, 2000

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


                                 THERMEDICS INC.
                 (Exact name of Registrant as specified in its charter)


Massachusetts               1-9567                                    04-2788806
(State or other           (Commission                           (I.R.S. Employer
jurisdiction of           File Number)                    Identification Number)
incorporation or
organization)


470 Wildwood Street, P.O. Box 2999
Woburn, Massachusetts                                                   01888
(Address of principal executive offices)                              (Zip Code)


                                 (781) 622-1000
                         (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  Thermedics
Inc.'s  Annual  Report on Form 10-K for the year ended  January  1, 2000.  These
include risks and uncertainties  relating to: government regulation and industry
standards,  competition and technological change,  intellectual property rights,
reimbursement by insurers for medical procedures,  medical community  acceptance
of medical devices, availability of materials and components, product liability,
international operations,  the company's acquisition strategy, and the company's
cash management arrangement with Thermo Electron.

Item 5.     Other Events

      On March 31, 2000, the Registrant issued a press release,  attached hereto
as Exhibit 99, regarding its previously announced tender offer for the shares of
common stock, $.01 par value per share, of its subsidiary Thermo Sentron Inc.

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

             99 Press Release dated March 31, 2000.






                                    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 31st day of March, 2000.



                                        THERMEDICS INC.



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






                                                                      Exhibit 99


Investor Contact: 781-622-1111
Media Contact: 781-622-1252

              Thermedics Completes Cash Tender Offer for Thermo Sentron

     WOBURN,  Mass.,  March  31,  2000 -  Thermedics  Inc.  (ASE-TMD),  a Thermo
Electron  company,  announced today that it has successfully  completed the cash
tender  offer of  $15.50  per share  for any and all  outstanding  shares of its
Thermo Sentron Inc. subsidiary.

     The offer and withdrawal rights expired at midnight on Thursday,  March 30,
2000. Based on the preliminary report of the depositary for the offer,  American
Stock Transfer & Trust Company,  approximately  1,144,000  Thermo Sentron shares
were tendered.  This brings  Thermedics' and Thermo  Electron's  combined equity
ownership in Thermo Sentron to approximately 98.6 percent. Thermedics expects to
complete the spin-in of Thermo Sentron by Tuesday, April 4, through a short-form
merger.  The  short-form  merger  does  not  require  Thermo  Sentron  board  or
shareholder approval.

     Shareholders  who  tendered  their  shares in the tender offer will receive
payment for their shares shortly.  Shareholders  who did not tender their shares
will  also  receive  $15.50  per  share in the  short-form  merger.  Information
outlining  what steps  these  Thermo  Sentron  shareholders  must take to obtain
payment will be mailed within a week to 10 days.

     The complete  terms and conditions of the tender offer are set forth in the
offer to purchase,  letter of transmittal,  and other related  materials,  which
were filed with the Securities and Exchange Commission on March 3, 2000.

     Thermedics Inc. develops,  manufactures, and markets diverse product lines,
including  implantable  heart-assist  devices  and  other  biomedical  products,
security  instruments,  and equipment that assures the quality of a wide variety
of consumer  products and bulk materials.  Thermedics is a public  subsidiary of
Thermo Electron  Corporation.  More  information is available on the Internet at
http://www.thermo.com/subsid/tmd1.html.

The following constitutes a "Safe Harbor" statement under the Private Securities
Litigation  Reform Act of 1995:  This  press  release  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 the  company's  annual report on Form 10-K for the
year ended January 1, 2000. These include risks and  uncertainties  relating to:
government  regulation and industry  standards,  competition  and  technological
change,  intellectual  property  rights,  reimbursement  by insurers for medical
procedures,  medical  community  acceptance of medical devices,  availability of
materials  and  components,   product   liability,   international   operations,
acquisition strategy,  and the company's cash management arrangement with Thermo
Electron.