SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549
               ---------------------------------------------------

                         AMENDMENT NO. 1 ON FORM 10-K/A
                                  TO FORM 10-K

(mark one)


  X     Annual Report Pursuant to Section 13 or 15(d) of the Securities Exchange
-----   Act of 1934

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


                          Commission file number 1-9567

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

Delaware                                                              04-2788806
(State or other jurisdiction of                                 (I.R.S. Employer
incorporation or organization)                               Identification No.)

470 Wildwood Street
Post Office Box 2999
Woburn, MA                                                            01888-1799
(Address of principal executive offices)                              (zip code)

       Registrant's telephone number, including area code: (781) 622-1000

           Securities registered pursuant to Section 12(b)of the Act:

                                                           Name of each exchange
Title of each class                                          on which registered
-------------------                                        ---------------------
Common Stock, $.10 par value                             American Stock Exchange

           Securities registered pursuant to section 12(g)of the Act:
                                      None

Indicate by check mark whether the Registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the preceding 12 months, and (2) has been subject to the filing requirements for
at least the past 90 days.  X   No    .
                           ----   ----

Indicate by check mark if disclosure of delinquent  filers  pursuant to Item 405
of Regulation  S-K is not contained  herein,  and will not be contained,  to the
best  of  the  Registrant's   knowledge,  in  definitive  proxy  or  information
statements  incorporated  by  reference  into  Part III of this Form 10-K or any
amendment to this Form 10-K. [ ]

The  aggregate  market  value of the voting stock held by  nonaffiliates  of the
Registrant as of January 28, 2000, was approximately $61,227,000.

As of January 28, 2000, the  Registrant  had  41,945,661  shares of Common Stock
outstanding.

                       DOCUMENTS INCORPORATED BY REFERENCE

Portions of the  Registrant's  Annual Report to Shareholders for the fiscal year
ended January 1, 2000, are incorporated by reference into Parts I and II.
<PAGE>


Items 10, 11, 12 and 13 of Part III of the  Registrant's  Annual  Report on Form
10-K for the fiscal year ended  January 1, 2000 are hereby  amended and restated
in their entirety as follows:

                                    Part III

Item 10 - DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT

DIRECTORS

         Set forth  below  are the names of the  directors,  their  ages,  their
offices in the Corporation, if any, their principal occupation or employment for
the past five years,  the length of their tenure as  directors  and the names of
other public  companies in which such  persons hold  directorships.  Information
regarding their beneficial  ownership of the Corporation's  Common Stock and the
common  stock  of its  subsidiaries  and its  parent  company,  Thermo  Electron
Corporation  ("Thermo  Electron"),  a  provider  of  products  and  services  in
measurement  instrumentation,  medical  devices,  power  generation and resource
recovery  is reported in Item 12 -  "Security  Ownership  of Certain  Beneficial
Owners and Management."

--------------------------------------------------------------------------------
T. Anthony Brooks       Mr. Brooks,  60, has been a director of Thermedics since
                        September  1998. Mr. Brooks was a managing  director and
                        member of the  operating  committee  of Lehman  Brothers
                        Inc. from 1991 until his  retirement  in 1997.  While at
                        Lehman  Brothers  Inc.,  Mr.  Brooks was the head of the
                        European    equity   division   from   1995   to   1996.
--------------------------------------------------------------------------------
Peter O. Crisp          Mr. Crisp,  67, has been a director of Thermedics  since
                        1983.  Mr.  Crisp  was  a  general  partner  of  Venrock
                        Associates,   for  more  than  five   years   until  his
                        retirement   in   September   1997.   He  has  been  the
                        vice-chairman of Rockefeller  Financial  Services,  Inc.
                        since  December  1997.  Mr.  Crisp is also a director of
                        American Superconductor Corporation,  Evans & Sutherland
                        Computer   Corporation,   Thermo  Electron  Corporation,
                        ThermoTrex   Corporation   and   United   States   Trust
                        Corporation.
--------------------------------------------------------------------------------
Paul F. Ferrari         Mr. Ferrari, 69, has been a director of Thermedics since
                        1991.  Mr.  Ferrari  was  a  vice  president  of  Thermo
                        Electron  from 1988 until his  retirement  at the end of
                        1990. Mr. Ferrari is also a director of General Scanning
                        Inc. and ThermoTrex Corporation.
--------------------------------------------------------------------------------
John T.  Keiser         Mr. Keiser,  64, has been a director of Thermedics since
                        April  1997.   He  has  been  the  president  and  chief
                        executive  officer of  Thermedics  since  March 1998 and
                        December 1998, respectively. From 1994 until March 1998,
                        Mr.  Keiser was a senior vice  president of  Thermedics.
                        Mr.  Keiser  has  been  the  chief  operating   officer,
                        biomedical, of Thermo Electron since September 1998, and
                        a vice president from April 1997 until his promotion. He
                        has also been the president of Thermo  Electron's wholly
                        owned  biomedical   group,  a  manufacturer  of  medical
                        equipment and  instruments,  since 1994. Mr. Keiser is a
                        director   of  Metrika   Systems   Corporation,   Thermo
                        Cardiosystems Inc., ThermoLase  Corporation,  ThermoTrex
                        Corporation and Trex Medical Corporation.
--------------------------------------------------------------------------------
John W. Wood Jr.        Mr. Wood,  56, has been a director of  Thermedics  since
                        1984 and  chairman of the board  since  March 1998.  Mr.
                        Wood  was  president  and  chief  executive  officer  of
                        Thermedics  from 1984 to March 1998. Mr. Wood has been a
                        senior vice president of Thermo  Electron since December
                        1995, and was a vice  president of Thermo  Electron from
                        September 1994 to December 1995.
--------------------------------------------------------------------------------
Nicholas T. Zervas      Dr. Zervas,  70, has been a director of Thermedics since
                        1987.  Dr.  Zervas was Chief of  Neurosurgical  Service,
                        Massachusetts  General  Hospital,  from 1977 until 2000.
                        Dr.  Zervas is also a director  of Thermo  Cardiosystems
                        Inc., ThermoLase Corporation and ThermoTrex Corporation.
--------------------------------------------------------------------------------
<PAGE>

COMMITTEES OF THE BOARD OF DIRECTORS AND MEETINGS

         The board of directors has  established an audit  committee and a human
resources  committee,  each consisting solely of directors who are not employees
of the Corporation, of Thermo Electron or of any other companies affiliated with
Thermo  Electron  ("outside  directors").  The  present  members  of  the  audit
committee  are Mr.  Ferrari  (Chairman),  Mr.  Crisp and Dr.  Zervas.  The audit
committee  reviews  the scope of the audit  with the  Corporation's  independent
public  accountants and meets with them for the purpose of reviewing the results
of the audit  subsequent  to its  completion.  The present  members of the human
resources committee are Mr. Crisp (Chairman) and Dr. Zervas. The human resources
committee  reviews the  performance of senior  members of  management,  approves
executive  compensation and administers the Corporation's stock option and other
stock-based  compensation  plans.  The  Corporation  does not have a  nominating
committee of the board of directors.  The board of directors met five times, the
audit  committee  met twice and the human  resources  committee  met three times
during fiscal 1999.  Each director  attended at least 75% of all meetings of the
board of  directors  and  committees  on which he served  that were held  during
fiscal 1999, except Mr. Ferrari who attended 71% of all meetings of the board of
directors and committees on which he served that were held during fiscal 1999.

         In 1998,  the board of directors  established a special  committee (the
"Special  Committee")  consisting solely of outside directors for the purpose of
evaluating  the merits and  negotiating  the terms of the proposed  transactions
with  Thermo  Electron  pursuant to which the  Company  would be taken  private,
considering  such  alternatives as the Special  Committee deems  appropriate and
making a  recommendation  to the full  board of  directors  on whether or not to
approve  any  such  proposed  transaction.  In  January  2000,  Thermo  Electron
determined not to proceed with this proposed transaction, but instead decided to
proceed with an exchange offer and merger. See Item 13 - "Certain  Relationships
and Related Transactions." As a result, the duties of the Special Committee were
modified  to review  the terms of the  proposed  exchange  offer and  merger and
either  recommend,  reject or take no  position  with  respect  to the  proposed
exchange offer and merger.  The members of the Special  Committee are Mr. Brooks
and Dr. Zervas.

COMPENSATION OF DIRECTORS

         CASH COMPENSATION

         Outside  directors  receive an annual  retainer  of $4,000 and a fee of
$1,000 per meeting for attending  regular meetings of the board of directors and
$500 per meeting for participating in meetings of the board of directors held by
means of  conference  telephone  and for  participating  in certain  meetings of
committees  of the  board  of  directors.  Payment  of  directors'  fees is made
quarterly.  Mr. Keiser and Mr. Wood are both employees of Thermo Electron or its
subsidiaries and do not receive any cash  compensation  from the Corporation for
their services as directors.  Directors are also  reimbursed  for  out-of-pocket
expenses incurred in attending such meetings.

         In addition,  the members of the Special Committee  receive a quarterly
fee of $15,000 and a fee of $1,000 per day for attending regular meetings of the
Special  Committee and $500 per day for participating in meetings of the Special
Committee held by means of conference telephone.

         DEFERRED COMPENSATION PLAN

         Under the Corporation's  deferred  compensation plan for directors (the
"Deferred  Compensation Plan"), a director has the right to defer receipt of his
cash fees  until he  ceases to serve as a  director,  dies or  retires  from his
principal occupation.  In the event of a change of control or proposed change of
control  of the  Corporation  that is not  approved  by the board of  directors,
deferred amounts become payable immediately.  Any of the following are deemed to
be a change of control:  (i) the acquisition by any person of 40% or more of the
outstanding  common  stock or voting  securities  of Thermo  Electron;  (ii) the
failure of the  Thermo  Electron  board of  directors  to include a majority  of
directors  who are  "continuing  directors",  which  term is  defined to include
directors  who were  members of Thermo  Electron's  board on July 1, 1999 or who
subsequent to that date were nominated or elected by a majority of directors who
were  "continuing  directors" at the time of such nomination or election;  (iii)
the consummation of a merger, consolidation, reorganization, recapitalization or
statutory  share  exchange  involving  Thermo  Electron  or the  sale  or  other
disposition of all or substantially  all of the assets of Thermo Electron unless
immediately  after such  transaction  (a) all holders of Thermo  Electron common
stock immediately prior to such transaction own more than 60% of the outstanding
voting securities of the resulting or acquiring corporation in substantially the
same  proportions as their ownership  immediately  prior to such transaction and
(b) no person after the transaction  owns 40% or more of the outstanding  voting
securities  of the
<PAGE>

resulting  or  acquiring  corporation;  or (iv)  approval by  stockholders  of a
complete  liquidation  or  dissolution  of  Thermo  Electron.  Amounts  deferred
pursuant to the Deferred Compensation Plan are valued at the end of each quarter
as units of Common Stock. When payable, amounts deferred may be disbursed solely
in shares of Common Stock accumulated under the Deferred  Compensation  Plan. As
of January 1, 2000 a total of 30,000  shares of Common  Stock has been  reserved
for issuance  under the Deferred  Compensation  Plan and deferred units equal to
25,238 shares of Common Stock were accumulated  under the Deferred  Compensation
Plan.

         DIRECTORS STOCK OPTION PLAN

         The  Corporation's  directors stock option plan (the "Directors  Plan")
provides for the grant of stock  options to purchase  shares of Common Stock and
the common  stock of its  majority-owned  subsidiaries  to outside  directors as
additional  compensation  for their  service as  directors.  Under the Directors
Plan,  outside  directors  receive an annual grant of options to purchase  1,000
shares  of  Common  Stock at the close of  business  on the date of each  Annual
Meeting of the Stockholders of the Corporation. Options evidencing annual grants
are  immediately  exercisable  at any time from and after the grant  date of the
option and generally on the third anniversary of the grant date.

         The exercise price for options  granted under the Directors Plan is the
average of the closing  prices of the common  stock as reported on the  American
Stock  Exchange  (or other  principal  market on which the common  stock is then
traded) for the five trading days  immediately  preceding and including the date
of grant,  or, if the  shares are not then  traded,  at the last price per share
paid by third parties in an arms-length  transaction  prior to the option grant.
As of January 31, 2000,  options to purchase  20,800 shares of Common Stock were
outstanding  under the  Directors  Plan,  options to purchase  36,700  shares of
Common Stock had been granted, options to purchase 12,600 shares of Common Stock
had lapsed, options to purchase 3,300 shares of Common Stock had been exercised,
and options to purchase  13,400 shares of Common Stock were available for future
grant.

STOCK OWNERSHIP POLICY FOR DIRECTORS

         The  human   resources   committee  of  the  board  of  directors  (the
"Committee")  has  established a stock holding policy for  directors.  The stock
holding  policy  requires  each  director  to hold a minimum of 1,000  shares of
Common Stock.  Directors are requested to achieve this ownership  level within a
three-year period. The chief executive officer of the Corporation is required to
comply with a separate stock holding policy established by the Committee,  which
is described below.

EXECUTIVE OFFICERS

         Reference  is made to Item 1(e) of this Annual  Report on Form 10-K for
information regarding the Executive Officers of the Registrant.

Item 11 - EXECUTIVE COMPENSATION

SUMMARY COMPENSATION TABLE

         The  following  table  summarizes  compensation  during  the last three
fiscal  years for  services to the  Corporation  in all  capacities  awarded to,
earned  by or  paid  to the  Corporation's  chief  executive  officer,  and  its
executive  officers  whose  total  annual  salary and bonus,  as  determined  in
accordance with the rules of the Securities and Exchange Commission, was greater
than $100,000,  and who were employed by the Corporation as of the end of fiscal
1999. These officers are together referred to as the "named executive officers."

         The Corporation is required to appoint certain  executive  officers and
full-time employees of Thermo Electron as executive officers of the Corporation,
in accordance with the Thermo Electron Corporate  Charter.  The compensation for
these executive officers is determined and paid entirely by Thermo Electron. The
time and effort  devoted by these  individuals to the  Corporation's  affairs is
provided to the Corporation under the Corporate  Services  Agreement between the
Corporation  and  Thermo  Electron.  See Item 13 -  "Certain  Relationships  and
Related  Transactions."  Accordingly,  the compensation for these individuals is
not reported in the following table.



<PAGE>



<TABLE>
<CAPTION>
<S>                          <C>       <C>       <C>           <C>              <C>                 <C>
                                              SUMMARY COMPENSATION TABLE
--------------------------------------------------------------------------------------------------------------------
                                                            Long Term Compensation
                                                             ---------------------
                                    Annual Compensation    Restricted       Securities
    Name and                Fiscal                            Stock         Underlying            All Other
Principal Position           Year    Salary     Bonus       Award (1)       Options (2)        Compensation (3)
-------------------         ------   ------     ------      ---------       ------------       ----------------

John T. Keiser (3)           1999   $45,000     $21,000    $28,689 (TMD) (4) 110,700 (TMD)      $7,200
  President and Chief                                                            700 (TCA)
  Executive Officer          1998   $63,000     $42,000         --            60,700 (TMD)      $7,200
                                                                              17,000 (TDX)
                                                                              25,000 (TCA)
                                                                              12,000 (TSR)
-------------------------------------------------------------------------------------------------------------------
Victor L. Poirier            1999  $200,000     $110,000   $185,625 (TCA) (5)  3,300 (TMD)      $7,200
  Senior Vice President                                                        1,100 (TMO)
                                                                               3,200 (TCA)
                             1998  $170,000     $100,000        --             3,100 (TMD)      $7,200
                                                                               3,798 (TMO)
                                                                               2,000 (MKA)
                                                                               2,000 (ONX)
                                                                               4,000 (RGI)
                                                                              93,200 (TCA)
                                                                                 999 (THI)
                                                                               1,023 (TKN)
                                                                               2,000 (TRIL)
                             1997  $160,000      $108,000       --             3,600 (TMD)       $7,125
                                                                                 800 (TMO)
                                                                              34,500 (TCA)
--------------------------------------------------------------------------------------------------------------------
</TABLE>

(1)      Options  granted  by  the  Corporation  are  designated  as  "TMD."  In
         addition,  the named executive  officers have also been granted options
         to purchase  common stock of the following  Thermo  Electron  companies
         during the last three fiscal years as part of Thermo  Electron's  stock
         option  program:  Thermo  Electron  (designated  in the  table as TMO),
         Metrika  Systems  Corporation  (designated  in the table as MKA),  ONIX
         Systems Inc. (designated in the table as ONX), The Randers Killam Group
         Inc.  (designated  in the  table as  RGI),  Thermedics  Detection  Inc.
         (designated in the table as TDX), Thermo Cardiosystems Inc. (designated
         in the table as TCA), Thermo Instrument Systems Inc. (designated in the
         table as THI),  Thermo  Sentron Inc.  (designated in the table as TSR),
         ThermoTrex  Corporation  (designated  in the  table as TKN) and  Thermo
         Trilogy Corporation (designated in the table as TRIL).

(2)      Represents   the  amount  of   matching   contributions   made  by  the
         individual's  employer  on  behalf  of  the  named  executive  officers
         participating in the Thermo Electron 401(k) plan.

(3)      Mr. Keiser was appointed president of the Corporation in March 1998 and
         chief executive  officer in December 1998. The annual cash compensation
         (salary and bonus) reported in the table for Mr. Keiser  represents the
         amount  paid by the  Corporation  solely for Mr.  Keiser's  services as
         president and chief executive officer of the Corporation in fiscal 1999
         and 1998. For fiscal 1999, 15% of Mr. Keiser's annual cash compensation
         (salary and bonus) was paid by the  Corporation  solely for his service
         as  president  and chief  executive  officer  of the  Corporation,  the
         remainder of Mr. Keiser's  compensation was paid by Thermo Electron and
         ThermoTrex  Corporation for Mr. Keiser's services in various management
         capacities.  For the last three  fiscal  quarters  of 1998,  35% of Mr.
         Keiser's  annual cash  compensation  (salary and bonus) was paid by the
         Corporation  solely for his service as  president  and chief  executive
         officer of the Corporation,  the remainder of Mr. Keiser's compensation
         was paid by  Thermo  Electron  for Mr.  Keiser's  services  in  various
         management  capacities.  The  options  reported  in the table have been
         granted by the  Corporation or its  majority-owned  subsidiaries to Mr.
         Keiser as  compensation  solely for his  services as the  Corporation's
         chief executive officer or as a director of its subsidiaries. From time
         to time Mr. Keiser has been, and in the future may be, granted  options
         to purchase common stock of Thermo Electron and its subsidiaries  other
         than the  Corporation.  These  options are not reported in the table as
         they are  granted as  compensation  for  service  to such other

<PAGE>

         Thermo Electron  companies in capacities  other than in his capacity as
         an executive officer of the Corporation.

(4)      In fiscal  1999,  Mr.  Keiser was awarded  3,000  shares of  restricted
         Common  Stock of the  Corporation  with a value of $28,689 on the grant
         date. The restricted stock award vests 100% on the third anniversary of
         the grant  date.  Any cash  dividends  paid on  restricted  shares  are
         entitled to be retained by the recipient without regard to vesting. Any
         non-cash  dividends  paid  on  restricted  shares  are  entitled  to be
         retained by the recipient  subject to the same vesting  restrictions as
         the underlying stock. At the end of fiscal 1999, Mr.
         Keiser held 3,000 restricted shares with an aggregate value of $16,314.

(5)      In fiscal 1999,  Mr.  Poirier was awarded  19,800  shares of restricted
         common stock of Thermo  Cardiosystems  Inc. with a value of $185,625 on
         the grant date. The restricted stock award vests 33% per year beginning
         on the first  anniversary of the grant date. Any cash dividends paid on
         restricted  shares are entitled to be retained by the recipient without
         regard to vesting. Any non-cash dividends paid on restricted shares are
         entitled to be retained by the  recipient  subject to the same  vesting
         restrictions  as the underlying  stock.  At the end of fiscal 1999, Mr.
         Poirier  held  19,800  restricted  shares  with an  aggregate  value of
         $129,947.

STOCK OPTIONS GRANTED DURING FISCAL 1999

         The following table sets forth information concerning individual grants
of stock options made during fiscal 1999 to the  Corporation's  named  executive
officers.  It has not been the  Corporation's  policy in the past to grant stock
appreciation rights, and no such rights were granted during fiscal 1999.




<TABLE>
<CAPTION>
<S>                              <C>                 <C>             <C>         <C>           <C>           <C>
                                                 OPTION GRANTS IN FISCAL 1999
-------------------------------------------------------------------------------------------------------------------
                                                                                            Potential Realizable
                                                   Percent of                                 Value at Assumed
                         Number of Securities    Total Options                             Annual Rates of Stock
                           Underlying Options      Granted to      Exercise                 Price Appreciation for
                              Granted and        Employees in     Price Per   Expiration       Option Term (2)
Name                          Company (1)         Fiscal Year       Share        Date          5%           10%
----                          -----------         ------------      -----        ----          ---          ----
John T. Keiser (3)          110,000 (TMD)             68.6%        $9.64      1/27/06       $431,680    $1,006,016
                                700 (TMD)              0.4%        $7.14      3/30/02           $790        $1,654
                                700 (TCA)              0.5%        $9.39       3/4/02         $1,040        $2,176
-------------------------------------------------------------------------------------------------------------------
Victor L. Poirier             3,300 (TMD)              2.1%         $7.14     3/30/02         $3,710        $7,799
                              1,100 (TMO)             0.04% (4)    $14.81     9/22/04         $4,500        $9,946
                              3,200 (TCA)              2.1%         $9.39      3/4/02         $4,740        $9,946
-------------------------------------------------------------------------------------------------------------------
</TABLE>

(1)      All of the  options  granted  during  the fiscal  year are  immediately
         exercisable  as of the end of the fiscal  year.  Generally,  the shares
         acquired  upon  exercise  are  subject to  repurchase  by the  granting
         company at the exercise price if the optionee  ceases to be employed by
         the granting company or any other Thermo Electron company. The granting
         company may exercise its repurchase  rights within six months after the
         termination  of  the  optionee's  employment.   The  repurchase  rights
         generally lapse ratably over a one- to five-year  period,  depending on
         the option term,  which may vary from three- to seven- years,  provided
         that the optionee  continues to be employed by the granting  company or
         another Thermo Electron company.  Certain options have three-year terms
         and the  repurchase  rights  lapse  in  their  entirety  on the  second
         anniversary  of the grant  date.  The  granting  company may permit the
         holders of options to exercise  options and to satisfy tax  withholding
         obligations  by  surrendering  shares equal in fair market value to the
         exercise price or withholding obligation. Please see footnote (1) under
         the Summary  Compensation  Table for the company  abbreviations used in
         this table.

(2)      The amounts shown in this table represent hypothetical gains that could
         be achieved for the  respective  options if exercised at the end of the
         option  term.   These  gains  are  based  on  assumed  rates  of  stock
         appreciation  of 5% and 10%  compounded  annually  from  the  date  the
         respective  options were granted to their  expiration  date.  The gains
         shown  are  net of  the  option  exercise  price,  but  do not  include
         deductions  for taxes or other  expense  associated  with the exercise.
         Actual  gains,  if any, on stock  option  exercises  will depend on the
         future  performance  of the common stock of the granting  company,  the
         optionee's  continued employment through the option period and the date
         on which the options are exercised.

<PAGE>


(3)      Mr.  Keiser  has been,  and in the future  may be,  granted  options to
         purchase  common stock of Thermo  Electron and its  subsidiaries  other
         than the  Corporation.  These  options are not reported in the table as
         they are  granted as  compensation  for  service  to such other  Thermo
         Electron  companies  in  capacities  other than in his  capacity  as an
         executive officer of the Corporation.

(4)      These  options were granted  under stock  option  plans  maintained  by
         Thermo  Electron  companies  other than the Corporation and accordingly
         are reported as a percentage of total  options  granted to employees of
         Thermo Electron and its subsidiaries.

STOCK OPTIONS EXERCISED DURING FISCAL 1999 AND FISCAL YEAR-END OPTION VALUES

         The following table reports certain information  regarding stock option
exercises  during fiscal 1999 and  outstanding  stock options held at the end of
fiscal 1999 by the Corporation's named executive officers. No stock appreciation
rights were exercised or were outstanding during fiscal 1999.


<TABLE>
<CAPTION>
<S>                           <C>                <C>            <C>               <C>                   <C>
                    AGGREGATED OPTION EXERCISES IN FISCAL 1999 AND FISCAL 1999 YEAR-END OPTION VALUES
----------------------------------------------------------------------------------------------------------------------
                                                                                                      Value of
                                                                               Number of           Unexercised
                                                                               Securities          In-the-Money
                                                                               Underlying           Options at
                                                                           Unexercised Options      Fiscal Year
                                                Shares                      at Fiscal Year-End         -End
                                             Acquired on        Value         (Exercisable/       (Exercisable/
        Name               Company (1)         Exercise     Realized (2)    Unexercisable) (1)    Unexercisable)
        ----               -----------         --------     ------------    ------------------   --------------
John T. Keiser (3)            (TMD)               --             --              187,900 /0              $0 /--
                              (TDX)               --             --               17,000 /0              $0 /--
                              (TCA)               --             --               50,200 /0              $0 /--
                              (TSR)               --             --               19,500 /0         $32,790 /--
----------------------------------------------------------------------------------------------------------------------
Victor L. Poirier             (TMD)               --             --               25,000 /0              $0 /--
                              (TMO)               --             --               46,123 /0 (4)        $684 /--
                              (MKA)               --             --                2,000 /0              $0 /--
                              (ONX)               --             --                2,000 /0              $0 /--
                              (RGI)               --             --                4,000 /0          $1,000 /--
                              (TBA)               --             --                2,000 /0         $16,750 /--
                              (TCA)             36,000        $125,640           211,450 /0 (5)          $0 /--
                              (TFG)               --             --                2,000 /0          $4,376 /--
                              (TFT)              4,500         $20,250                -- /--             -- /--
                              (THI)               --             --                1,702 /0          $3,067 /--
                              (TLZ)               --             --                5,000 /0              $0 /--
                              (TLT)               --             --                   -- /2,000          -- /$0   (6)
                              (TOC)               --             --                6,000 /0          $5,430 /--
                              (TMQ)               --             --                6,000 /0              $0 /--
                              (TSR)               --             --                7,500 /0          $3,750 /--
                              (TKN)               --             --                1,023 /--            $56 /--
                             (TRIL)               --             --                   -- /2,000          -- /$0   (6)
                              (TXM)               --             --                4,000 /0              $0 /--
----------------------------------------------------------------------------------------------------------------------
</TABLE>

(1)      All of the options  reported  outstanding at the end of the fiscal year
         were immediately  exercisable as of the end of the fiscal year,  except
         options to purchase the common stock ThermoLyte  Corporation and Thermo
         Trilogy Corporation, which are not exercisable until the earlier of (i)
         90 days after the effective date of the  registration  of the company's
         common  stock under  Section 12 of the  Exchange Act or (ii) nine years
         after the grant date.  Generally,  the shares acquired upon exercise of
         the  options  reported in the table are  subject to  repurchase  by the
         granting  company at the exercise  price if the  optionee  ceases to be
         employed  by, or serve as a  director  of,  such  company  or any other
         Thermo  Electron  company.   The  granting  company  may  exercise  its
         repurchase  rights  within  six  months  after the  termination  of the
         optionee's employment or cessation of directorship, as the case may be.
         For  publicly-traded  companies,

<PAGE>

         the repurchase  rights  generally lapse ratably over a one- to ten-year
         period,  depending  on the  option  term,  which may vary from three to
         twelve years, provided that the optionee continues to be employed by or
         serve as a director of the granting  company or another Thermo Electron
         company.  For  companies  whose  shares  are not  publicly-traded,  the
         repurchase  rights lapse in their entirety on the ninth  anniversary of
         the  grant  date.   Certain  options  have  three-year  terms  and  the
         repurchase rights lapse in their entirety on the second  anniversary of
         the grant date.  The granting  company may permit the holder of options
         to  exercise  options  and to satisfy tax  withholding  obligations  by
         surrendering shares equal in fair market value to the exercise price or
         withholding  obligation.  Please  see  footnote  (1) under the  Summary
         Compensation Table for the company  abbreviations used in this table in
         addition to the following  company  abbreviations:  Thermo  BioAnalysis
         Corporation  (designated  in the table as TBA),  Thermo  Fibergen  Inc.
         (designated in the table as TFG),  Thermo Fibertek Inc.  (designated in
         the table as TFT), ThermoLase  Corporation  (designated in the table as
         TLZ), ThermoLyte  Corporation  (designated in the table as TLT), Thermo
         Optek  Corporation  (designated  in the  table  as TOC),  Thermo  Quest
         Corporation   (designated  in  the  table  as  TMQ)  and  Trex  Medical
         Corporation (designated in the table as TXM).


(2)      Amounts shown in this column do not necessarily  represent actual value
         realized  from the sale of the shares  acquired  upon  exercise  of the
         option  because in many cases the shares are not sold on  exercise  but
         continue  to be held by the  executive  officer  after  exercising  the
         option.  The amounts shown represent the difference  between the option
         exercise  price and the market price on the date of exercise,  which is
         the amount  that would have been  realized  if the shares had been sold
         immediately upon exercise.

(3)      Mr. Keiser was first  appointed an officer of the  Corporation  in July
         1994. From time to time after that date, he has been, and in the future
         may be, granted options to purchase common stock of Thermo Electron and
         its  subsidiaries  other than the  Corporation.  These  options are not
         reported in the table as they are granted as  compensation  for service
         to such other Thermo Electron companies in capacities other than in his
         capacity as an executive officer of the Corporation.

(4)      Options  to  purchase  22,500  shares  of the  common  stock of  Thermo
         Electron  granted  to Mr.  Poirier  are  subject  to the same  terms as
         described in footnote  (1),  except that the  repurchase  rights of the
         granting company  generally do not lapse until the tenth anniversary of
         the grant date.  In the event of the  employee's  death or  involuntary
         termination  prior to the  tenth  anniversary  of the grant  date,  the
         repurchase  rights  of the  granting  company  shall be  deemed to have
         lapsed  ratably  over a  five-year  period  commencing  with the  fifth
         anniversary of the grant date.

(5)      Options  to  purchase  30,000  shares  of the  common  stock of  Thermo
         Cardiosystems Inc. granted to Mr. Poirier are subject to the same terms
         as described in footnote (1),  except that the repurchase  rights lapse
         20% per year commencing on the sixth anniversary of the grant date.

(6)      No public market existed for the shares  underlying these options as of
         January 1, 2000. Accordingly,  no value in excess of the exercise price
         has been attributed to these options.

EXECUTIVE RETENTION AGREEMENTS

         Thermo  Electron has entered  into  agreements  with certain  executive
officers and key employees of Thermo Electron and its subsidiaries  that provide
severance  benefits if there is a change in control of Thermo Electron and their
employment is terminated by Thermo Electron "without cause" or by the individual
for  "good  reason,"  as those  terms  are  defined  therein,  within  18 months
thereafter.  For purposes of these  agreements,  a change in control exists upon
(i) the acquisition by any person of 40% or more of the outstanding common stock
or voting securities of Thermo Electron; (ii) the failure of the Thermo Electron
board of  directors  to  include a majority  of  directors  who are  "continuing
directors",  which  term is defined to  include  directors  who were  members of
Thermo  Electron's  board on the date of the agreement or who  subsequent to the
date of the agreement  were  nominated or elected by a majority of directors who
were  "continuing  directors" at the time of such nomination or election;  (iii)
the consummation of a merger, consolidation, reorganization, recapitalization or
statutory  share  exchange  involving  Thermo  Electron  or the  sale  or  other
disposition of all or substantially  all of the assets of Thermo Electron unless
immediately  after such  transaction  (a) all holders of Thermo  Electron common
stock immediately prior to such transaction own more than 60% of the outstanding
voting securities of the resulting or acquiring corporation in substantially the
same  proportions as their ownership  immediately  prior
<PAGE>

to such  transaction and (b) no person after the transaction owns 40% or more of
the outstanding voting securities of the resulting or acquiring corporation;  or
(iv) approval by stockholders of a complete liquidation or dissolution of Thermo
Electron.

         In 1998, Thermo Electron  authorized an executive  retention  agreement
with each of Mr.  John T. Keiser and Mr.  Victor L.  Poirier.  These  agreements
provide  that in the event  the  individual's  employment  is  terminated  under
circumstances  described  above,  the individual would be entitled to a lump sum
payment equal to the sum of (a) in the case of Mr. Keiser two times,  and in the
case of Mr. Poirier,  one times, the individual's  highest annual base salary in
any 12 month period during the prior five-year  period,  plus (b) in the case of
Mr.  Keiser,  two  times,  and in  the  case  of Mr.  Poirier,  one  times,  the
individual's  highest  annual  bonus in any 12 month  period  during  the  prior
five-year period.  In addition,  the individual would be provided benefits for a
period of, in the case of Mr. Keiser, two years, and in the case of Mr. Poirier,
one year,  after  such  termination  substantially  equivalent  to the  benefits
package  the  individual  would have been  otherwise  entitled to receive if the
individual was not terminated. Further, all repurchase rights of Thermo Electron
and its  subsidiaries  shall lapse in their entirety with respect to all options
and  restricted  stock  that the  individual  holds in Thermo  Electron  and its
subsidiaries,  including  the  Corporation,  as of the  date  of the  change  in
control.  Finally,  the individual would be entitled to a cash payment equal to,
in the case of Mr. Keiser, $20,000, and in the case of Mr. Poirier,  $15,000, to
be used toward  outplacement  services.  These  executive  retention  agreements
supercede  and  replace  any and all prior  severance  arrangements  which these
individuals had with Thermo Electron.

         Assuming  that the  severance  benefits  would have been  payable as of
January 1, 2000,  the lump sum salary and bonus payment under such  agreement to
Messrs. Keiser and Poirier would have been approximately  $920,000 and $364,500,
respectively. In the event that payments under these agreements are deemed to be
so called "excess  parachute  payments"  under the applicable  provisions of the
Internal  Revenue Code of 1986, as amended (the "Internal  Revenue  Code"),  the
individuals  would be entitled to receive a gross-up payment equal to the amount
of any excise tax payable by such  individual  with respect to such payment plus
the amount of all other additional taxes imposed on such individual attributable
to the receipt of such gross-up payment.

STOCK OWNERSHIP POLICY

         The  Committee has  established  a stock  holding  policy for the chief
executive  officer of the Corporation that requires him to own a multiple of his
compensation in shares of the  Corporation's  Common Stock.  The multiple is one
times  his  base  salary  and  reference  bonus  for the  fiscal  year in  which
compliance  is achieved.  The chief  executive  officer has three years from the
adoption of the policy to achieve this ownership level.

         In order to assist the chief  executive  officer in complying  with the
policy,  the Committee also adopted a stock holding  assistance plan under which
the Corporation is authorized to make interest-free loans to the chief executive
officer to enable him to purchase shares of Common Stock in the open market. Any
loans  are  required  to be  repaid  upon the  earlier  of  demand  or the tenth
anniversary  of the  date  of  the  loan,  unless  otherwise  determined  by the
Committee.  No loans were outstanding  under this program in 1999. See Item 13 -
"Certain  Relationships  and Related  Transactions  - Stock  Holding  Assistance
Plan."

Item 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

         The following  table sets forth, as of January 31, 2000, the beneficial
ownership of Common Stock, as well as the common stock of Thermo  Electron,  the
Corporation's  parent  company,  and of Thermedics  Detection Inc.  ("Thermedics
Detection"),  Thermo  Cardiosystems  Inc. ("Thermo  Cardiosystems"),  and Thermo
Sentron  Inc.  ("Thermo  Sentron"),  each  a  majority-owned  subsidiary  of the
Corporation,  with respect to (i) each  director,  (ii) each  executive  officer
named  in  the  summary   compensation   table  under  the  heading   "Executive
Compensation"  (the "named  executive  officers")  and (iii) all  directors  and
current  executive  officers  as a  group.  The  common  stock  of  each  of the
majority-owned  subsidiaries  is publicly  traded except for the common stock of
Thermedics  Detection and Thermo  Sentron which have,  subsequent to January 31,
2000,  been taken  private.  In  addition,  the  following  table sets forth the
beneficial  ownership of Common Stock,  as of January 31, 2000,  with respect to
each person who was known by the Corporation to own beneficially more than 5% of
the outstanding shares of Common Stock.

         While certain  directors and executive  officers of the Corporation are
also  directors and executive  officers of Thermo  Electron or its  subsidiaries
other than the Corporation,  all such persons disclaim  beneficial  ownership of
the shares of Common Stock owned by Thermo Electron.

<PAGE>
<TABLE>
<CAPTION>
<S>                                         <C>           <C>               <C>              <C>            <C>
                                                        Thermo          Thermedics        Thermo
                                        Thermedics     Electron          Detection     Cardiosystems  Thermo Sentron
            Name (1)                     Inc.(2)     Corporation (3)     Inc. (4)        Inc. (5)         Inc. (6)
            --------                     -------     ---------------     --------        --------         ---------
Thermo Electron Corporation (7)....... 31,759,424             N/A             N/A             N/A              N/A
T. Anthony Brooks.....................      5,367               0               0               0                0
Peter O. Crisp........................     37,076         121,767               0           2,250                0
Paul F. Ferrari.......................     11,050          16,482             599          11,500                0
John T. Keiser........................    194,693         331,636          17,000          57,473           19,500
Victor L. Poirier.....................     69,455          53,880               0         283,772            7,500
John W. Wood Jr.......................    233,200         293,550          37,251          46,207           35,000
Nicholas T. Zervas....................     22,064               0               0          44,924                0
All directors and current executive
   officers as a group (8 persons)....    584,766       1,275,847          54,850         469,672           62,000
</TABLE>



(1)      Except as reflected in the footnotes to this table, shares beneficially
         owned consist of shares owned by the indicated person or by that person
         for the benefit of minor  children,  and all share  ownership  includes
         sole voting and investment power.

(2)      Shares of the Common Stock beneficially owned by Mr. Brooks, Mr. Crisp,
         Mr. Ferrari,  Mr. Keiser,  Mr. Poirier,  Mr. Wood and all directors and
         current  executive  officers as a group include  1,000,  9,000,  8,950,
         187,900,  25,000, 174,150 and 406,000 shares,  respectively,  that such
         person or group had the right to acquire  within 60 days of January 31,
         2000, through the exercise of stock options.  Shares beneficially owned
         by all  directors  and current  executive  officers as a group  include
         1,119 shares  allocated  through January 31, 2000, to their  respective
         accounts  maintained  pursuant  to  Thermo  Electron's  employee  stock
         ownership plan (the "ESOP").  Shares  beneficially owned by Mr. Brooks,
         Mr. Crisp, Dr. Zervas and all directors and current executive  officers
         as  a  group  include   1,367,   9,971,   10,364  and  21,702   shares,
         respectively, that had been allocated through January 1, 2000, to their
         respective  accounts  maintained under the Deferred  Compensation Plan.
         Shares  beneficially  owned by Mr. Wood  include  2,600  shares held in
         custodial  accounts for the benefit of his minor children.  No director
         or named  executive  officer  beneficially  owned  more  than 1% of the
         Common Stock  outstanding  as of January 31, 2000;  all  directors  and
         current executive  officers as a group  beneficially owned 1.39% of the
         Common Stock outstanding as of such date.

(3)      Shares of the common stock of Thermo Electron beneficially owned by Mr.
         Crisp, Mr. Keiser, Mr. Poirier,  Mr. Wood and all directors and current
         executive officers as a group include 25,596, 263,230,  46,123, 249,298
         and  968,608  shares,  respectively,  that such person or group has the
         right to  acquire  within 60 days of  January  31,  2000,  through  the
         exercise of stock options.  Shares  beneficially owned by all directors
         and  current  executive  officers  as  a  group  include  1,071  shares
         allocated to their respective accounts maintained pursuant to the ESOP.
         Shares  beneficially  owned by Mr. Crisp and all  directors and current
         executive  officers as a group each include  49,277  allocated  through
         January 1, 2000, to Mr. Crisp's account  maintained  pursuant to Thermo
         Electron's  deferred  compensation  plan for directors.  No director or
         named executive officer  beneficially  owned more than 1% of the Thermo
         Electron common stock outstanding as of January 31, 2000; all directors
         and current executive  officers as a group beneficially owned less than
         1% of such common stock outstanding as of such date.

(4)      Shares of the common stock of Thermedics  Detection  beneficially owned
         by Mr.  Keiser,  Mr.  Wood  and all  directors  and  current  executive
         officers  as  a  group  include  20,000,   17,000  and  37,000  shares,
         respectively, that such person or group has the right to acquire within
         60 days of January 31, 2000, through the exercise of stock options.  No
         director or named executive officer  beneficially owned more than 1% of
         the  Thermedics  Detection  common stock  outstanding as of January 31,
         2000;  all  directors  and  current  executive   officers  as  a  group
         beneficially  owned less than 1% of such common stock outstanding as of
         such date.

(5)      Shares of the common stock of Thermo  Cardiosystems  beneficially owned
         by Mr. Crisp,  Mr.  Ferrari,  Mr. Keiser,  Mr.  Poirier,  Mr. Wood, Dr.
         Zervas and all  directors  and  current  executive  officers as a group
         include  2,250,  2,250,  50,200,  211,450,  23,450,  6,600 and  316,200
         shares,  respectively,  that  such  person  or group  has the  right to
         acquire  within 60 days of January 31,  2000,  through the  exercise of
         stock  options.  Shares  beneficially  owned  by  Dr.  Zervas  and  all
         directors and current executive  officers as a group each include 9,074
         shares  allocated  through  January 1,  2000,  to Dr.  Zervas'  account
         maintained pursuant to Thermo Cardiosystems' deferred compensation plan
         for  directors.  Shares

<PAGE>

         beneficially  owned by Mr. Wood include  1,122 shares held in custodial
         accounts  for the benefit of his minor  children.  Shares  beneficially
         owned by Dr.  Zervas  include  19,000  shares  held by his  spouse.  No
         director or named executive officer  beneficially owned more than 1% of
         the Thermo  Cardiosystems  common stock  outstanding  as of January 31,
         2000;  all  directors  and  current  executive   officers  as  a  group
         beneficially owned approximately 1.22% of such common stock outstanding
         on such date.

(6)      Shares of the common stock of Thermo Sentron  beneficially owned by Mr.
         Keiser,  Mr. Poirier,  Mr. Wood and all directors and current executive
         officers as a group include  19,500,  7,500,  31,000 and 58,000 shares,
         respectively, that such person or group has the right to acquire within
         60 days of January 31, 2000, through the exercise of stock options.  No
         director or named executive officer  beneficially owned more than 1% of
         the Thermo Sentron common stock outstanding as of January 31, 2000; all
         directors and current executive  officers as a group beneficially owned
         less than 1% of such common stock outstanding as of such date.

(7)      Thermo Electron  beneficially owned approximately  75.72% of the Common
         Stock outstanding as of January 31, 2000. Thermo Electron's  address is
         81 Wyman Street, Waltham, Massachusetts 02454-9046.

SECTION 16(A) BENEFICIAL OWNERSHIP REPORTING COMPLIANCE

         Section 16(a) of the Exchange Act requires the Corporation's  directors
and executive  officers,  and  beneficial  owners of more than 10% of the Common
Stock,  such as  Thermo  Electron,  to file  with the  Securities  and  Exchange
Commission  initial  reports of  ownership  and  periodic  reports of changes in
ownership of the Corporation's securities.  Based upon a review of such filings,
all Section 16(a) filing  requirements  applicable to such persons were complied
with during 1999,  except in the following  instance.  Thermo Electron filed one
Form  4  late  reporting  a  total  of  17  transactions   associated  with  the
cancellation  and grant of options to purchase Common Stock granted to employees
under its stock option program.

Item 13 -  CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS

         The Charter,  the  Corporation  and Thermo Electron have entered into a
Corporate  Services  Agreement  (the  "Services  Agreement")  under which Thermo
Electron's corporate staff provides certain administrative  services,  including
certain  legal  advice  and  services,   risk   management,   employee   benefit
administration,  tax advice and  preparation  of tax returns,  centralized  cash
management and financial and other services to the Corporation.  The Corporation
was assessed an annual fee equal to 0.8% of the Corporation's revenues for these
services  for  fiscal  1999.   The  annual  fee  will  remain  at  0.8%  of  the
Corporation's  total revenues for fiscal 2000. The fee is reviewed  annually and
may be changed  by mutual  agreement  of the  Corporation  and Thermo  Electron.
During fiscal 1999, Thermo Electron assessed the Corporation  $1,788,000 in fees
under the Services  Agreement.  Management  believes  that the charges under the
Services  Agreement are reasonable and that the terms of the Services  Agreement
are fair to the  Corporation.  In fiscal  1999,  the  Corporation  was billed an
additional  $56,318  by Thermo  Electron  for  certain  administrative  services
required by the Corporation that were not covered by the Services Agreement. The
Services Agreement  automatically  renews for successive  one-year terms, unless
canceled  by the  Corporation  upon 30 days'  prior  notice.  In  addition,  the
Services Agreement terminates  automatically in the event the Corporation ceases
to be a Thermo  subsidiary or ceases to be a participant in the Thermo  Electron
Charter.  In  the  event  of  a  termination  of  the  Services  Agreement,  the
Corporation  will be required to pay a termination fee equal to the fee that was
paid by the  Corporation  for  services  under the  Services  Agreement  for the
nine-month period prior to termination.  Following termination,  Thermo Electron
may provide  certain  administrative  services on an  as-requested  basis by the
Corporation or as required in order to meet the Corporation's  obligations under
Thermo  Electron's  policies and  procedures.  Thermo  Electron  will charge the
Corporation  a fee equal to the  market  rate for  comparable  services  if such
services are provided to the Corporation following termination.

         As of January 1, 2000,  the  Corporation  owed Thermo  Electron and its
other subsidiaries an aggregate of $3,121,000 for amounts due under the Services
Agreement and related  administrative  charges,  for other products and services
and for  miscellaneous  items,  net of amounts owed to the Corporation by Thermo
Electron and its other subsidiaries for products, services and for miscellaneous
items.  The largest amount of such net  indebtedness  owed by the Corporation to
Thermo Electron and its other subsidiaries since January 2, 1999 was $7,138,000.
These  amounts do not bear  interest  and are  expected to be paid in the normal
course of business.

<PAGE>


         Thermedics  Detection  purchases  an  X-ray  source  that  is used as a
component  in its  InScan  systems  from Trex  Medical  Corporation,  a publicly
traded,  majority-owned  subsidiary  of ThermoTrex  Corporation  ("ThermoTrex"),
which is itself a publicly traded, majority-owned subsidiary of Thermo Electron.
Thermedics Detection paid Trex Medical Corporation $81,000 for these products in
fiscal 1999.

         Pursuant  to an  international  distributorship  agreement,  Thermedics
Detection  appointed  Arabian  Business  Machines Co.  ("ABM") as its  exclusive
distributor  of Thermedics  Detection's  security  instruments in certain Middle
Eastern countries.  ABM is a member of the Olayan Group. Ms. Hutham S. Olayan, a
director of Thermo  Electron,  is the president and a director of Olayan America
Corporation,  a member of The Olayan Group,  which is  indirectly  controlled by
Suliman S. Olayan,  Ms. Olayan's father.  Revenues recorded under this agreement
totaled $147,000 in fiscal 1999.

         In June 1998,  Thermo Sentron borrowed $21 million from Thermo Electron
pursuant to a promissory note due December 1998,  bearing interest at the 90-day
Commercial  Paper  Composite Rate plus 25 basis points,  set at the beginning of
each  quarter.  Thermo  Sentron  entered  into this  note in order to  partially
finance  its  acquisition  of  the  three   businesses   that   constituted  the
product-monitoring  group of Graseby Limited,  a subsidiary of Smiths Industries
plc  ("Graseby"),  for  $44  million  in  cash,  net of cash  acquired,  and the
assumption of certain  liabilities.  In December 1998,  Thermo Sentron repaid $2
million of this amount and issued Thermo  Electron a new promissory note for $19
million in exchange for the initial  note.  This note is due June 1999 and bears
interest under the same terms as the initial note.  Subsequently,  in June 1999,
Thermo  Sentron  repaid  $6million  of this amount and issued a new note for $13
million.  Thermo  Sentron repaid an additional $1 million under the note in each
of the  third  and  fourth  quarters  of 1999.  In March  2000,  Thermo  Sentron
refinanced the note under the Thermo Electron Cash Management  arrangement which
bears interest at a rate equal to the 30-day Dealer  Commercial  Paper Rate plus
150 basis  points set at the  beginning  of each month and was 7.55% at April 1,
2000.

         In January  2000,  Thermo  Sentron  entered  into a fifteen  year lease
arrangement  with Thermo  Electron  with respect to Thermo  Sentron's  principal
executive offices in Minneapolis,  Minnesota. The rent payable by Thermo Sentron
to Thermo Electron under the lease is $50,000 per month for the first five years
of the  lease,  $55,000  per month for the  second  five  years of the lease and
$60,000 per month for the final fives years of the lease.

         Thermo Sentron acts as a distributor in Europe for process  measurement
instruments  manufactured by another Thermo Subsidiary.  In 1999, Thermo Sentron
purchased such products from this Thermo Subsidiary for $326,000.

         Thermo Electron's Tecomet division provides metal fabrication  services
in connection  with the  manufacture  of the heart assist devices sold by Thermo
Cardiosystems.  During 1999, Thermo  Cardiosystems  paid Tecomet  $3,651,000 for
these services.

         On February 5, 1998,  the  Corporation's  board of  directors  voted to
issue  4,880,533  shares of Common Stock to Thermo Electron in exchange for 100%
of the  stock  of TMO TCA  Holdings,  Inc.,  which  is the  beneficial  owner of
3,355,705  shares of Thermo  Cardiosystems'  common stock.  Thermo  Electron had
acquired such shares of Thermo  Cardiosystems  common stock as consideration for
the acquisition by Thermo Cardiosystems of International  Technidyne Corporation
("ITC") from Thermo Electron in May 1997. The Thermo  Cardiosystems  shares were
valued at $75,000,000 at the time of the acquisition by Thermo  Cardiosystems of
ITC. The issuance of the 3,355,705 shares of Thermo  Cardiosystems' common stock
was subject to the approval of Thermo Cardiosystems' stockholders of the listing
of such shares for trading on the American Stock Exchange, which was obtained at
a special meeting of the stockholders of Thermo  Cardiosystems held on April 13,
1998.  The  Corporation's  issuance of the  4,880,533  shares of Common Stock to
Thermo Electron was subject to approval by the Corporation's stockholders, which
was obtained at a special  meeting of the  Stockholders  held on March 31, 1999.
The number of shares of Common Stock was determined based on the respective fair
market values of the Common Stock and the Thermo  Cardiosystems  common stock as
of February 5, 1998.  The fair market values of the  4,880,553  shares of Common
Stock  and the  3,355,705  shares  of Thermo  Cardiosystems  common  stock as of
February 5, 1998 were each $75,587,000.

         The Corporation, along with other U.K.-based Thermo Electron companies,
participates  in a notional pool  arrangement  in the U.K.  with Barclays  Bank,
which includes a $114,943,000  credit  facility.  The  Corporation has access to
$6,065,000  under  this  credit  facility.  Under  this  arrangement,   Barclays
notionally  combines  the  positive  and  negative  cash  balances  held  by the
participants  to calculate  the net interest

<PAGE>

yield/expense  for the group.  The benefit derived from this arrangement is then
allocated based on balances attributable to the respective participants.  Thermo
Electron  guarantees  all  of  the  obligations  of  each  participant  in  this
arrangement.  As of January 1, 2000, the Corporation had a positive cash balance
of  approximately  and a $1,441,000 and a negative cash balance of approximately
$2,640,000 based on an exchange rate of $1.6171/GBP  1.00. For 1999, the average
annual  interest  rate  earned on GBP  deposits by  participants  in this credit
arrangement was approximately 5.44% and the average annual interest rate paid on
overdrafts was approximately 5.8025%.

         At year-end 1998,  $35,256,000 of the  Corporation's  cash  equivalents
were  invested  in a  repurchase  agreement  with  Thermo  Electron.  Under this
agreement,  the Corporation in effect lent excess cash to Thermo Electron, which
Thermo  Electron  collateralized  with  investments  principally  consisting  of
corporate notes, U.S.  government  agency  securities,  commercial paper,  money
market funds and other marketable securities,  in the amount of at least 103% of
such obligation.  The  Corporation's  funds subject to the repurchase  agreement
were readily convertible into cash by the Corporation.  The repurchase agreement
earned a rate based on the 90-day  Commercial Paper Composite Rate plus 25 basis
points, set at the beginning of each quarter.

         Effective June 1999, the Corporation and Thermo Electron  commenced use
of a new  domestic  cash  management  arrangement.  Under  the new  arrangement,
amounts  advanced  to Thermo  Electron  by the  Corporation  for  domestic  cash
management  purposes bear interest at the 30-day  Dealer  Commercial  Paper Rate
plus 50 basis  points,  set at the beginning of each month.  Thermo  Electron is
contractually  required to maintain cash, cash equivalents,  and/or  immediately
available bank lines of credit equal to at least 50% of all funds invested under
this cash management  arrangement by all Thermo Electron subsidiaries other than
wholly owned subsidiaries. The Corporation has the contractual right to withdraw
its  funds  invested  in the cash  management  arrangement  upon 30 days'  prior
notice.  At year-end 1999, the Corporation had invested  $46,285,000  under this
arrangement.   In  addition,   certain  of  the   Corporation's   European-based
subsidiaries  participate  in a new cash  management  arrangement  with a wholly
owned  subsidiary  of Thermo  Electron  on terms  similar to the  domestic  cash
management  arrangement.  The  Corporation  has access to a $36,473,000  line of
credit under this  arrangement,  of which the Corporation had invested  $411,000
and had borrowed  $34,600,000 at year-end 1999.  Interest under this arrangement
is calculated  based on Euro market rates and was 3.95% on the negative  balance
at year-end 1999.

         The  Corporation,  along with certain  other Thermo  subsidiaries,  has
entered into a cash management  arrangement  with ABN AMRO. Only  European-based
Thermo  Subsidiaries  participate in this arrangement.  The new arrangement with
ABN AMRO consists of a zero balance  arrangement,  which  includes a $25,417,000
credit  facility.  The  Corporation  has access to $2,280,000  under this credit
facility.  Funds borrowed by the Corporation under this arrangement pay interest
at a rate set by  Thermo  Finance  B.V.,  a  wholly-owned  subsidiary  of Thermo
Electron,  at the beginning of each month,  based on  Netherlands  market rates.
Funds  invested  by the  Corporation  under the  arrangement  earn a rate set by
Thermo Finance B.V. at the beginning of each month,  based on Netherlands market
rates.  Such invested  funds are  collateralized  with  investments  principally
consisting of corporate notes,  U.S.  government-agency  securities,  commercial
paper, money market funds, and other marketable securities,  in the amount of at
least 103% of such obligation. Thermo Electron guarantees all of the obligations
of each participant in this arrangement.  As of January 2, 1999, the Corporation
had a negative cash balance of approximately $698,000, based on an exchange rate
of $0.4599/NLG  1.00. As of January 1, 2000,  the average  annual  interest rate
earned  on  NLG  deposits  by  participants  in  this  credit   arrangement  was
approximately  3.19% and the average annual interest rate paid on overdrafts was
approximately 3.74%.

THERMO ELECTRON CORPORATE REORGANIZATION

         Thermo  Electron has adopted a major  reorganization  plan under which,
among  other  things,  it is  acquiring  the  minority  interest  in most of its
subsidiaries that have minority  investors.  In furtherance of this plan, Thermo
Electron  intends  to  commence  an  exchange  offer  for  any  and  all  of the
outstanding  shares of common stock of the Corporation that it does not own. The
consideration  being  offered  in the  exchange  offer is .45  shares  of Thermo
Electron common stock for each share of the Corporation's common stock. The goal
of the exchange  offer is to bring  Thermo  Electron's  equity  ownership in the
Corporation  to at least 90%. If Thermo  Electron  achieves  this  90%-ownership
level, the Corporation would then be taken private through a "short-form" merger
at the same exchange ratio as the exchange offer.  In addition,  as part of this
reorganization  plan, the Corporation  completed the acquisition of the minority
interest in each of its Thermo Voltek,  Thermo Sentron and Thermedics  Detection
subsidiaries.  The consideration  paid in each of these  transactions was $7.00,
$15.50 and $8.00 per share in cash, respectively, without interest.

<PAGE>


         Executive  officers and directors of the Corporation who held shares of
common stock in the Corporation's  subsidiaries  described above that were taken
private  received the same cash  consideration  per share of subsidiary stock as
all  other  stockholders  of  such  subsidiaries.  In  addition,  the  executive
officers' and directors' options to acquire shares of such subsidiaries'  common
stock,  for which the granting  corporation's  repurchase  rights had not lapsed
("unvested  options"),  were automatically  assumed by either the Corporation or
Thermo Electron, as applicable, and converted into options to purchase shares of
the  Corporation's  common stock or Thermo  Electron's  common stock on the same
terms as were applicable to all the other holders of such subsidiary's  options,
as  described  below.  In  the  case  of  options  to  acquire  shares  of  such
subsidiaries'  common  stock,  for which the granting  corporation's  repurchase
rights had lapsed ("vested options"),  the holders were given the opportunity to
elect either to convert the options into vested options to acquire shares of the
Corporation's common stock or Thermo Electron's common stock, as applicable,  or
to receive cash at the  applicable  cash  transaction  price less the applicable
exercise price, on the same terms as were applicable to all the other holders of
such subsidiary's options.

         Vested and unvested  options that were  assumed by the  Corporation  or
Thermo  Electron in these  completed  transactions  generally  were converted as
follows:  The  number  of  shares of the  Corporation's  common  stock or Thermo
Electron's  common stock  underlying  each assumed  option equaled the number of
shares of subsidiary  common stock underlying the option before the transaction,
multiplied by the applicable "cash exchange ratio" described below, rounded down
to the  nearest  whole  number of shares of the  Corporation's  common  stock or
Thermo  Electron's  common stock. The exercise price for each assumed option was
calculated by dividing the exercise price of the subsidiary  stock option before
the transaction by the applicable "cash exchange ratio" described below, rounded
up to the nearest whole cent.  The  applicable  "cash  exchange  ratio" for each
transaction was a fraction, the numerator of which was the applicable cash price
described  above  and the  denominator  of which  was the  closing  price of the
Corporation's common stock or Thermo Electron's common stock, as applicable,  on
the day preceding the effective date of the transaction.

         Additionally,   certain   directors   participated   in  the   deferred
compensation plans of the various subsidiaries. On the effective date of each of
the completed cash transactions listed above, each of the affected subsidiaries'
deferred  compensation plans terminated and the participants received cash in an
amount equal to the balance of such participant's stock units credited to his or
her account under the respective deferred  compensation plan,  multiplied by the
applicable  cash price described  above.  Any such stock units held by directors
are included in their stock ownership information described below.

         In the Thermo Voltek Corp. transaction, Mr. Melas-Kyriazi (who is not a
named  executive  officer of the  Corporation  for  purposes of  Securities  and
Exchange Commission regulations,  and whose ownership information therefore does
not appear in such stock ownership table)and Mr. Wood received a cash payment of
$7.00 per share for 5,581 and  14,621  shares of common  stock of Thermo  Voltek
Corp.  held by such  individuals,  respectively.  Additionally,  Mr. Crisp,  Mr.
Ferrari,  Mr. Wood and Mr. Zervas held options to acquire 2,250,  2,250,  82,350
and 2,250 shares of Thermo Voltek Corp.  common stock,  respectively,  that were
converted into options to acquire shares of common stock of the Corporation,  as
described above.

         In the Thermedics Detection Inc. transaction,  Mr. Ferrari and Mr. Wood
received a cash  payment of $8.00 per share for 599 and 17,251  shares of common
stock of  Thermedics  Detection  Inc.  held by such  individuals,  respectively.
Additionally,  Mr. Keiser and Mr. Wood held options to acquire 17,000 and 20,000
shares of  Thermedics  Detection  Inc.  common  stock,  respectively,  that were
converted into options to acquire  shares of Thermo  Electron  common stock,  as
described above.

         In the  Thermo  Sentron  Inc.  transaction,  Mr.  Wood  received a cash
payment of $15.50 per share for 4,000 shares of common  stock of Thermo  Sentron
Inc. held by Mr. Wood.  Additionally,  Mr. Keiser, Mr. Poirier and Mr. Wood held
options to acquire 19,500, 7,500 and 31,000 shares of Thermo Sentron Inc. common
stock,  respectively,  that were  converted  into  options to acquire  shares of
Thermo Electron common stock, as described above.

         Executive  officers and directors of the Corporation who hold shares of
the Corporation's common stock will receive the same consideration per share for
such stock as all other  stockholders of the Corporation.  See Item 12 "Security
Ownership of Certain Beneficial Owners and Management."

         In  addition,   certain   executive   officers  and  directors  of  the
Corporation  hold options to acquire  shares of common stock of the  Corporation
(See  Item  12  -  "Security   Ownership  of  Certain   Beneficial   Owners  and
Management"),  which  options will be treated in the same manner as options held
by other  employees.  All options held by such persons will be assumed by Thermo
Electron  and  converted  into  options to acquire  shares

<PAGE>

of Thermo Electron's common stock on the same terms as are applicable to all the
other holders of the Corporation's options.

         Specifically,  vested and unvested  options  that are being  assumed by
Thermo Electron in the proposed  transaction  will be converted as follows:  The
number of shares of Thermo Electron common stock  underlying each assumed option
will equal the number of shares of the Corporation  common stock  underlying the
option before the transaction, multiplied by the exchange ratio, rounded down to
the nearest whole number of shares of Thermo Electron common stock. The exercise
price for each assumed  option will be calculated by dividing the exercise price
of the  Corporation  stock option before the  transaction by the exchange ratio,
rounded up to the nearest whole cent.

         In addition to the ownership  information that appears in the Item 12 -
"Security  Ownership of Certain  Beneficial  Owners and Management"  table,  Mr.
Melas-Kyriazi holds 11,861 shares of common stock of the Corporation.

         On the effective date of the proposed  transaction,  the  Corporation's
deferred  compensation  plan will be assumed by Thermo  Electron,  and the stock
units  credited to each  participant's  account under the deferred  compensation
plan will be converted into stock units for Thermo  Electron common stock at the
exchange ratio.

STOCK HOLDING ASSISTANCE PLAN

         The human resources  committee of the Corporation's  board of directors
(the  "Committee")  established a stock  holding  policy that requires its chief
executive  officer  to  acquire  and hold a  minimum  number of shares of Common
Stock.  In order to assist the chief  executive  officer in  complying  with the
policy,  the Committee also adopted a stock holding  assistance plan under which
the Corporation may make interest-free  loans to the chief executive officer, to
enable him to purchase Common Stock in the open market.  Loans will be repayable
upon the  earlier  of demand or the tenth  anniversary  of the date of the loan,
unless otherwise determined by the Committee.  No such loans were outstanding in
1999.

                                   SIGNATURES

Pursuant to the  requirements of Section 13 or 15(d) of the Securities  Exchange
Act of 1934,  the Registrant has duly caused this Amendment No. 1 on Form 10-K/A
to be signed by the undersigned, duly authorized.

                                              THERMEDICS INC.


                                              By: / s /  Sandra L. Lambert
                                                 ------------------------------
                                                 Sandra L. Lambert
                                                 Clerk