SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

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                                    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):

                               September 29, 1998

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                                 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
Woburn, Massachusetts                                            01888
 (Address of principal executive offices)                      (Zip Code)


                                 (781) 938-3786
                         (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 3, 1998.
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,  Thermedics Inc.'s spinout and acquisition
strategies,   and  the   potential   impact  of  the  year  2000  on  processing
date-sensitive information.

Item 5.     Other Events

      On September 29, 1998, Thermedics Inc.'s majority-owned  subsidiary Thermo
Cardiosystems  Inc. ("Thermo  Cardiosystems")  issued a press release announcing
that  the  U.S.  Food  and  Drug  Administration  ("FDA")  has  approved  Thermo
Cardiosystems' electric HeartMate(R) left ventricular-assist system ("LVAS") for
commercial sale as a bridge to heart transplant.  The electric HeartMate LVAS is
an implantable heart-assist system designed to allow heart-transplant candidates
to return home while waiting for a donor heart.

      In addition,  on September 29, 1998,  Baxter Healthcare  Corporation,  the
principal U.S. operating subsidiary of Baxter International Inc., announced that
it has  received  pre-market  approval  from  the FDA for  its  Novacor(R)  Left
Ventricular Assist System in the United States as a bridge to heart transplant.

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 30th day of September, 1998.



                                          THERMEDICS INC.



                                          By:/s/ Kenneth J. Apicerno
                                             Kenneth J. Apicerno
                                             Treasurer