SECURITIES AND EXCHANGE COMMISSION


                              Washington, DC 20549

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

                                    FORM 10-Q

    (mark one)

    [ X ] Quarterly Report Pursuant to Section 13 or 15(d) of the Securities
          Exchange Act of 1934 for the Quarter Ended March 29, 1997.

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

                          Commission File Number 1-9786


                         THERMO INSTRUMENT SYSTEMS INC.
             (Exact name of Registrant as specified in its charter)

    Delaware                                                       04-2925809
    (State or other jurisdiction of                          (I.R.S. Employer
    incorporation or organization)                        Identification No.)

    1275 Hammerwood Avenue
    Sunnyvale, California                                               94089
    (Address of principal executive offices)                       (Zip Code)


       Registrant's telephone number, including area code: (617) 622-1000

              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 (or for such shorter
              period that the Registrant was required to file such
              reports), and (2) has been subject to such filing
              requirements for the past 90 days. Yes [ X ] No [   ]
                 
              Indicate the number of shares outstanding of each of
              the issuer's classes of Common Stock, as of the
              latest practicable date.

                     Class                 Outstanding at April 25, 1997
          ----------------------------     -----------------------------
          Common Stock, $.10 par value               97,214,545
PAGE
<PAGE>
    PART I - FINANCIAL INFORMATION

    Item 1 - Financial Statements

                         THERMO INSTRUMENT SYSTEMS INC.

                           Consolidated Balance Sheet
                                   (Unaudited)

                                     Assets


                                                     March 29,  December 28,
    (In thousands)                                        1997          1996
    ------------------------------------------------------------------------
    Current Assets:
      Cash and cash equivalents                     $  432,256    $  522,688
      Available-for-sale investments, at quoted
        market value (amortized cost of $7,470
        and $7,430)                                      7,477         7,452
      Accounts receivable, less allowances
        of $20,711 and $16,981                         363,049       303,331
      Unbilled contract costs and fees                   7,720         6,043
      Inventories:
        Raw materials and supplies                     122,729        95,920
        Work in process                                 59,478        47,518
        Finished goods                                 103,020        70,245
      Prepaid expenses                                  25,436        13,417
      Prepaid income taxes                              71,037        58,296
                                                    ----------    ----------
                                                     1,192,202     1,124,910
                                                    ----------    ----------

    Property, Plant, and Equipment, at Cost            306,107       250,976
      Less: Accumulated depreciation and
            amortization                                76,741        72,313
                                                    ----------    ----------
                                                       229,366       178,663
                                                    ----------    ----------
    Patents and Other Assets                            31,691        32,454
                                                    ----------    ----------
    Cost in Excess of Net Assets of Acquired
      Companies (Note 3)                               930,862       588,373
                                                    ----------    ----------
                                                    $2,384,121    $1,924,400
                                                    ==========    ==========








                                        2PAGE
<PAGE>
                         THERMO INSTRUMENT SYSTEMS INC.

                     Consolidated Balance Sheet (continued)
                                   (Unaudited)

                    Liabilities and Shareholders' Investment

                                                    March 29,  December 28,
    (In thousands except share amounts)                  1997          1996
    -----------------------------------------------------------------------
    Current Liabilities:
      Notes payable                                $  189,598    $   89,462
      Accounts payable                                102,002        83,161
      Accrued payroll and employee benefits            57,597        51,728
      Accrued income taxes                             51,677        39,686
      Accrued installation and warranty expenses       45,854        44,211
      Accrued acquisition expenses (Note 3)            42,245        30,025
      Deferred revenue                                 45,258        35,959
      Other accrued expenses                          137,021       101,646
      Due to parent company                             9,293        12,329
                                                   ----------    ----------
                                                      680,545       488,207
                                                   ----------    ----------
    Deferred Income Taxes                              20,538        20,710
                                                   ----------    ----------
    Other Deferred Items                               27,944        29,805
                                                   ----------    ----------
    Long-term Obligations:
      Senior convertible obligations (includes
        $140,000 due to parent company)               330,784       334,781
      Subordinated convertible obligations            192,500       192,500
      Other (includes $235,000 and $15,000 due
        to parent company; Note 3)                    255,313        26,933
                                                   ----------    ----------
                                                      778,597       554,214
                                                   ----------    ----------
    Minority Interest                                 102,019        85,197
                                                   ----------    ----------

    Shareholders' Investment:
      Common stock, $.10 par value, 250,000,000
        shares authorized; 97,913,322 and
        97,674,228 shares issued                        9,791         9,767
      Capital in excess of par value                  323,682       319,464
      Retained earnings                               458,228       424,641
      Treasury stock at cost, 706,230 and
        750,055 shares                                 (8,405)       (8,679)
      Cumulative translation adjustment                (8,822)        1,060
      Net unrealized gain on available-for-sale
        investments                                         4            14
                                                   ----------    ----------
                                                      774,478       746,267
                                                   ----------    ----------
                                                   $2,384,121    $1,924,400
                                                   ==========    ==========

    The accompanying notes are an integral part of these consolidated
    financial statements.
                                        3PAGE
<PAGE>
                         THERMO INSTRUMENT SYSTEMS INC.

                        Consolidated Statement of Income
                                   (Unaudited)


                                                       Three Months Ended
                                                    ------------------------
                                                    March 29,      March 30,
    (In thousands except per share amounts)              1997           1996
    ------------------------------------------------------------------------
    Revenues                                         $329,120       $225,571
                                                     --------       --------

    Costs and Operating Expenses:
      Cost of revenues                                173,448        118,207
      Selling, general, and administrative expenses    89,569         65,709
      Research and development expenses                23,407         16,549
      Write-off of acquired technology                      -          3,500
                                                     --------       --------
                                                      286,424        203,965
                                                     --------       --------

    Operating Income                                   42,696         21,606

    Interest Income                                     7,224          5,111
    Interest Expense (includes $1,559 and $1,537
      to parent company)                               (8,460)        (6,290)
    Gain on Issuance of Stock by Subsidiaries
      (Note 4)                                         12,035         24,257
                                                     --------       --------
    Income Before Provision for Income Taxes
      and Minority Interest Expense                    53,495         44,684
    Provision for Income Taxes                         17,770         10,073
    Minority Interest Expense                           2,138            568
                                                     --------       --------
    Net Income                                       $ 33,587       $ 34,043
                                                     ========       ========
    Earnings per Share:
      Primary                                        $    .35       $    .37
                                                     ========       ========
      Fully diluted                                  $    .32       $    .33
                                                     ========       ========
    Weighted Average Shares:
      Primary                                          97,071         91,875
                                                     ========       ========
      Fully diluted                                   111,442        107,269
                                                     ========       ========


    The accompanying notes are an integral part of these consolidated
    financial statements.


                                        4PAGE
<PAGE>
                         THERMO INSTRUMENT SYSTEMS INC.

                      Consolidated Statement of Cash Flows
                                   (Unaudited)

                                                      Three Months Ended
                                                    -----------------------
                                                    March 29,     March 30,
    (In thousands)                                       1997          1996
    -----------------------------------------------------------------------
    Operating Activities:
      Net income                                    $  33,587     $  34,043
      Adjustments to reconcile net income to
        net cash provided by operating activities:
          Depreciation and amortization                11,662         9,036
          Provision for losses on accounts
            receivable                                  1,084           413
          Gain on issuance of stock by
            subsidiaries (Note 4)                     (12,035)      (24,257)
          Write-off of acquired technology                  -         3,500
          Minority interest expense                     2,138           568
          Decrease in deferred income taxes                 -           (40)
          Other noncash expenses                        1,419         1,138
          Changes in current accounts, excluding
            the effects of acquisitions:
              Accounts receivable                     (12,326)        8,814
              Inventories                             (10,436)       (6,998)
              Other current assets                     (7,745)        1,168
              Accounts payable                           (404)       (1,861)
              Other current liabilities                (1,439)        5,012
          Other                                           (28)          198
                                                    ---------     ---------
    Net cash provided by operating activities           5,477        30,734
                                                    ---------     ---------
    Investing Activities:
      Acquisitions, net of cash acquired (Note 3)    (336,935)     (239,406)
      Purchases of property, plant, and equipment      (3,989)       (5,370)
      Other                                               601         1,527
                                                    ---------     ---------
    Net cash used in investing activities            (340,323)     (243,249)
                                                    ---------     ---------
    Financing Activities:
      Net proceeds from issuance of Company and
        subsidiaries' common stock (Note 4)            25,219        42,010
      Short-term borrowings from parent company             -        89,012
      Proceeds from issuance of short-term
        obligation to parent company                        -        30,000
      Proceeds from issuance of long-term
        obligations to parent company (Note 3)        220,000             -
      Repayment of long-term obligations                 (253)       (1,139)
                                                    ---------     ---------
    Net cash provided by financing activities       $ 244,966     $ 159,883
                                                    ---------     ---------

                                        5PAGE
<PAGE>
                         THERMO INSTRUMENT SYSTEMS INC.

                Consolidated Statement of Cash Flows (continued)
                                   (Unaudited)

                                                      Three Months Ended
                                                    -----------------------
                                                    March 29,     March 30,
    (In thousands)                                       1997          1996
    -----------------------------------------------------------------------
    Exchange Rate Effect on Cash                    $    (552)    $    (128)
                                                    ---------     ---------
    Decrease in Cash and Cash Equivalents             (90,432)      (52,760)
    Cash and Cash Equivalents at Beginning
      of Period                                       522,688       395,233
                                                    ---------     ---------
    Cash and Cash Equivalents at End of Period      $ 432,256     $ 342,473
                                                    =========     =========

    Noncash Activities:
      Fair value of assets of acquired companies    $ 607,466     $ 494,240
      Cash paid for acquired companies               (383,247)     (251,964)
      Cash to be paid for remaining outstanding
        shares of tender offer                        (21,102)            -
      Issuance of subsidiary stock options
        for acquisition                                (2,080)            -
                                                    ---------     ---------
          Liabilities assumed of acquired companies $ 201,037     $ 242,276
                                                    =========     =========
      Conversions of convertible obligations        $   3,997     $  14,356
                                                    =========     =========


    The accompanying notes are an integral part of these consolidated
    financial statements.





                                        6PAGE
<PAGE>
                         THERMO INSTRUMENT SYSTEMS INC.

                   Notes to Consolidated Financial Statements

    1.  General

        The interim consolidated financial statements presented have been
    prepared by Thermo Instrument Systems Inc. (the Company) without audit
    and, in the opinion of management, reflect all adjustments of a normal
    recurring nature necessary for a fair statement of the financial position
    at March 29, 1997, the results of operations for the three-month periods
    ended March 29, 1997, and March 30, 1996, and the cash flows for the
    three-month periods ended March 29, 1997, and March 30, 1996. Interim
    results are not necessarily indicative of results for a full year.

        The consolidated balance sheet presented as of December 28, 1996, has
    been derived from the consolidated financial statements that have been
    audited by the Company's independent public accountants. The consolidated
    financial statements and notes are presented as permitted by Form 10-Q
    and do not contain certain information included in the annual financial
    statements and notes of the Company. The consolidated financial
    statements and notes included herein should be read in conjunction with
    the financial statements and notes included in the Company's Annual
    Report on Form 10-K for the fiscal year ended December 28, 1996, as
    amended, filed with the Securities and Exchange Commission.

    2.  Presentation

        Certain amounts in 1996 have been reclassified to the presentation in
    the 1997 financial statements.

    3.  Acquisitions

        In March 1997, the Company acquired 166,557,897 shares (or
    approximately 95%) of Life Sciences International PLC (Life Sciences), a
    London Stock Exchange-listed company, for 135 pence per share
    (approximately $2.15 per share, or an aggregate of approximately $362.7
    million, including related expenses) in completion of the Company's offer
    to acquire all of the outstanding shares of Life Sciences. The Company
    expects to acquire the Life Sciences shares that remain outstanding for
    135 pence per share pursuant to the compulsory acquisition rules
    applicable to United Kingdom companies. The accompanying balance sheet as
    of March 29, 1997, includes $21.1 million accrued for the purchase of the
    remaining Life Sciences shares outstanding, plus shares issuable upon
    exercise of outstanding stock options. Subsequent to the end of the
    quarter, the Company repaid approximately $75 million of Life Sciences'
    debt. Life Sciences manufactures laboratory science equipment,
    appliances, instruments, consumables, and reagents for the research,
    clinical, and industrial markets.

        To partially finance the acquisition of Life Sciences, the Company
    borrowed $210.0 million from Thermo Electron Corporation (Thermo
    Electron) pursuant to a promissory note due March 1999, and bearing
    interest at the Commercial Paper Composite Rate plus 25 basis points, set
    at the beginning of each quarter.

                                        7PAGE
<PAGE>
                         THERMO INSTRUMENT SYSTEMS INC.

    3.  Acquisitions (continued)

        During the first quarter of 1997, the Company made several other
    acquisitions for approximately $20.5 million in cash, the issuance of
    subsidiary stock options valued at an aggregate $2.1 million, and a
    subsidiary's issuance of a $10.0 million promissory note to Thermo
    Electron, which is due March 1999, and bears interest at the 90-day
    Commercial Paper Composite Rate plus 25 basis points, set at the
    beginning of each quarter.

        The acquisitions completed in the first quarter of 1997 have been
    accounted for using the purchase method of accounting and their results
    have been included in the accompanying financial statements from their
    respective dates of acquisition. The cost of these acquisitions exceeded
    the estimated fair value of the acquired net assets by $349.5 million,
    which is being amortized over 40 years. Allocation of the purchase price
    for these acquisitions was based on estimates of the fair value of the
    net assets acquired and is subject to adjustment upon finalization of the
    purchase price allocation.

        Based on unaudited data, the following table presents selected
    financial information for the Company and Life Sciences on a pro forma
    basis, assuming the companies had been combined since the beginning of
    1996. The effect of the acquisitions not included in the pro forma data
    was not material to the Company's results of operations.

                                                      Three Months Ended
                                                  --------------------------
                                                  March 29,        March 30,
    (In thousands except per share amounts)            1997             1996
    ------------------------------------------------------------------------
    Revenues                                       $381,892         $307,232
    Net income                                       20,485           30,813
    Earnings per share:
      Primary                                           .21              .34
      Fully diluted                                     .20              .30

        The pro forma results are not necessarily indicative of future
    operations or the actual results that would have occurred had the
    acquisition of Life Sciences been made at the beginning of 1996.

        During 1996, the Company had undertaken a restructuring of a
    substantial portion of the businesses comprising the Scientific
    Instruments Division of Fisons plc (Fisons), acquired in March 1996.
    During the first quarter of 1997, the Company expended $5.1 million for
    restructuring costs, primarily for severance and abandoned facility
    payments. In connection with finalizing its restructuring plans for the
    businesses acquired from Fisons, the Company recorded an additional $8.1
    million of acquisition reserves in the first quarter of 1997, primarily
    for the abandonment of excess facilities, as well as severance. This
    amount was recorded as an increase in cost in excess of net assets of
    acquired companies. The remaining reserve for restructuring these
    businesses was $20.6 million at March 29, 1997, which primarily
    represents ongoing severance and abandoned facility payments. As of March
    29, 1997, the Company has accrued $42.2 million in connection with

                                        8PAGE
<PAGE>
                         THERMO INSTRUMENT SYSTEMS INC.

    3.  Acquisitions (continued)

    restructuring activities of all of its acquisitions, including the
    businesses acquired from Fisons.

    4.  Issuance of Stock by Subsidiary

         In March 1997, the Company's ThermoQuest Corporation (ThermoQuest)
    subsidiary sold 1,768,500 shares of its common stock at $15.00 per share
    for net proceeds of approximately $25 million, resulting in a gain of
    approximately $12 million. Following the sale, the Company owned 90% of
    ThermoQuest's outstanding common stock.


    Item 2 - Management's Discussion and Analysis of Financial Condition and
             Results of Operations
  
        Forward-looking statements, within the meaning of Section 21E of the
    Securities Exchange Act of 1934, are made throughout this Management's
    Discussion and Analysis of Financial Condition and Results of Operations.
    For this purpose, any statements contained herein that are not statements
    of historical fact may be deemed to be forward-looking statements.
    Without limiting the foregoing, the words "believes," "anticipates,"
    "plans," "expects," "seeks," "estimates," and similar expressions are
    intended to identify forward-looking statements. There are a number of
    important factors that could cause the results of the Company to differ
    materially from those indicated by such forward-looking statements,
    including those detailed under the caption "Forward-looking Statements"
    in Exhibit 13 to the Company's Annual Report on form 10-K for the fiscal
    year ended December 28, 1996, filed with the Securities and Exchange
    Commission.

    Results of Operations

    First Quarter 1997 Compared With First Quarter 1996

        Revenues increased $103.5 million, or 46%, to $329.1 million in the
    first quarter of 1997 from $225.6 million in the first quarter of 1996
    due to acquisitions, which included Life Sciences International PLC (Life
    Sciences) in March 1997 (Note 3) and a substantial portion of the
    businesses comprising the Scientific Instruments Division of Fisons plc
    (Fisons) in March 1996. Acquisitions added revenues of $110.9 million in
    the first quarter of 1997. The increase in revenues from acquisitions was
    offset in part by a decrease of $8.0 million in revenues due to the
    unfavorable effects of currency translation as a result of the
    strengthening of the U.S. dollar relative to foreign currencies in
    countries in which the Company operates. An increase in revenues from
    ThermoQuest Corporation's (ThermoQuest) existing mass spectrometry
    business as a result of the continued success of a new product introduced
    in the first quarter of 1996 was offset by a decrease in revenues at
    certain of the Company's other existing businesses, principally Thermo
    Optek Corporation (Thermo Optek). Revenues from Thermo Optek's existing
    businesses decreased due to the inclusion in 1996 of several large
    nonrecurring sales to the Chinese and Japanese governments and the
    elimination of certain unprofitable acquired product lines.

                                        9PAGE
<PAGE>
                         THERMO INSTRUMENT SYSTEMS INC.

    First Quarter 1997 Compared With First Quarter 1996 (continued)

        International sales account for a significant portion of the
    Company's total revenues. Although the Company seeks to charge its
    customers in the same currency as its operating costs, the Company's
    financial performance and competitive position can be affected by
    currency exchange rate fluctuations. Where appropriate, the Company uses
    forward exchange contracts to reduce its exposure to currency
    fluctuations.

        The gross profit margin remained relatively unchanged at 47.3% in the
    first quarter of 1997, compared with 47.6% in the first quarter of 1996.
    An increase in ThermoQuest's gross profit margin, primarily due to the
    increase in sales of higher-margin mass spectrometry products, was more
    than offset by the inclusion of lower-margin revenues from acquired
    businesses, including Life Sciences, which recorded an adjustment to
    expense of $2.7 million relating to the revaluation of the finished goods
    inventories acquired by the Company.

        Selling, general, and administrative expenses as a percentage of
    revenues decreased to 27% in the first quarter of 1997 from 29% in the
    first quarter of 1996, primarily due to efforts at Thermo Optek to reduce
    selling and administrative costs at certain acquired businesses and the
    integration of products from businesses acquired from Fisons into Thermo
    Optek's existing distribution channels. Research and development expenses
    as a percentage of revenues remained relatively unchanged at 7.1% in
    1997, compared with 7.3% in 1996.

        In the first quarter of 1996, the Company wrote off $3.5 million of
    acquired technology in connection with the acquisition of a significant
    portion of the businesses comprising the Scientific Instruments Division
    of Fisons.

        Interest income increased to $7.2 million in the first quarter of
    1997 from $5.1 million in the first quarter of 1996, due to interest
    income earned on invested proceeds from the issuance of $172.5 million
    principal amount of 4 1/2% senior convertible debentures by the Company
    in October 1996 and, to a lesser extent, from the sale of common stock by
    ThermoQuest, Thermo BioAnalysis Corporation (Thermo BioAnalysis), and
    Metrika Systems Corporation (Metrika Systems) in 1996. The increase in
    interest income was offset in part by a reduction in cash as a result of
    acquisitions. Interest expense increased to $8.5 million in 1997 from
    $6.3 million in 1996, primarily due to the issuance of the 4 1/2% senior
    convertible debentures by the Company and, to a lesser extent, the
    inclusion of interest expense on debt assumed as part of the Fisons and
    Life Sciences acquisitions. Subsequent to the end of the quarter, the
    Company repaid approximately $75 million of Life Sciences' debt. The
    Company expects to repay the remaining $30 million of Life Sciences' debt
    in June 1997. The increases in interest expense were offset in part by
    the conversion of a portion of the Company's convertible obligations into
    common stock of the Company. Interest expense will increase as a result
    of an aggregate $220.0 million in promissory notes issued to Thermo
    Electron Corporation (Thermo Electron) in connection with acquisitions
    (Note 3).
                                       10PAGE
<PAGE>
                         THERMO INSTRUMENT SYSTEMS INC.

    First Quarter 1997 Compared With First Quarter 1996 (continued)

        The Company has adopted a strategy of spinning out certain of its
    businesses into separate subsidiaries and having these subsidiaries sell
    a minority interest to outside investors. The Company believes that this
    strategy provides additional motivation and incentives for the management
    of the subsidiaries through the establishment of subsidiary-level stock
    option incentive programs, as well as capital to support the
    subsidiaries' growth. As a result of the sale of stock by subsidiaries,
    the Company recorded gains of approximately $12 million in the first
    quarter of 1997 and $24 million in the first quarter of 1996 (Note 4).
    The size and timing of these transactions are dependent on market and
    other conditions that are beyond the Company's control. Accordingly,
    there can be no assurance that the Company will be able to realize gains
    from such transactions in the future.

        The effective tax rate increased to 33% in the first quarter of 1997
    from 23% in the first quarter of 1996, primarily due to a lower
    nontaxable gain on issuance of stock by subsidiaries in 1997. Excluding
    the impact of the gain on issuance of stock by subsidiaries in 1997 and
    1996, the effective tax rates in both periods exceeded the statutory
    federal income tax rate due to nondeductible amortization of cost in
    excess of net assets of acquired companies, the inability to provide a
    tax benefit on losses incurred at certain foreign subsidiaries, the
    impact of state income taxes, and in 1996, the write-off of acquired
    technology in connection with the acquisition of the businesses from
    Fisons.

        Minority interest expense increased to $2.1 million in the first
    quarter of 1997 from $0.6 million in the first quarter of 1996, primarily
    due to the minority interest associated with the Company's newly public
    ThermoQuest, Thermo Optek, and Thermo BioAnalysis subsidiaries.

    Liquidity and Capital Resources

        Consolidated working capital was $511.7 million at March 29, 1997,
    compared with $636.7 million at December 28, 1996. Included in working
    capital are cash, cash equivalents, and available-for-sale investments of
    $439.7 million at March 29, 1997, and $530.1 million at December 28,
    1996. Of the $439.7 million balance at March 29, 1997, $207.3 million was
    held by ThermoQuest, $61.5 million by Thermo Optek, $12.2 million by
    ThermoSpectra, $59.2 million by Thermo BioAnalysis, $17.4 million by
    Metrika Systems, and $82.1 million by the Company and its wholly owned
    subsidiaries. The Company's operating activities provided cash of $5.5
    million in the first quarter of 1997. Accounts receivable increased $12.3
    million primarily due to increased shipments by one of ThermoQuest's
    foreign subsidiaries in the first quarter of 1997, compared with the
    fourth quarter of 1996, and an increase in accounts receivable at Life
    Sciences from the date of its acquisition by the Company. Inventories
    increased $10.4 million primarily due to replenishing year-end levels,
    which had decreased by $17.2 million during the fourth quarter of 1996.

        At March 29, 1997, $104.6 million of the Company's cash and cash
    equivalents was held by its foreign subsidiaries. While this cash can be
    used outside of the United States, including for acquisitions,

                                       11PAGE
<PAGE>
                         THERMO INSTRUMENT SYSTEMS INC.

    Liquidity and Capital Resources (continued)

    repatriation of this cash into the United States would be subject to
    foreign withholding taxes and could also be subject to a United States
    tax.

        The Company's investing activities used $340.3 million of cash in the
    first quarter of 1997. The Company expended $336.9 million for
    acquisitions (Note 3) and $4.0 million for the purchase of property,
    plant, and equipment. Subsequent to the end of the quarter, the Company
    repaid approximately $75 million of Life Sciences' debt. The Company
    expects to repay the remaining $30 million of Life Sciences' debt in June
    1997. Such debt is included in current notes payable in the accompanying
    1997 balance sheet.

        The Company's financing activities provided $245.0 million of cash in
    the first quarter of 1997. In March 1997, to partially finance
    acquisitions, the Company borrowed an aggregate $220.0 million from
    Thermo Electron pursuant to promissory notes due March 1999 (Note 3). In
    March 1997, ThermoQuest sold shares of its common stock for net proceeds
    of approximately $25 million (Note 4). 

        In April 1997, Metrika Systems filed a registration statement under
    the Securities Act of 1933 with the Securities and Exchange Commission
    covering shares of common stock to be offered in its initial public
    offering.

        During the remainder of 1997, the Company plans to make expenditures
    of approximately $21 million for property, plant, and equipment. The
    Company believes that its existing resources are sufficient to meet the
    capital requirements of its existing operations for the foreseeable
    future. The Company has historically complemented internal development
    with acquisitions of businesses or technologies that extend the Company's
    presence in current markets or provide opportunities to enter and compete
    effectively in new markets. The Company will consider making acquisitions
    of such businesses or technologies that are consistent with its plans for
    strategic growth. The Company expects that it will finance these
    acquisitions through a combination of internal funds, additional debt or
    equity financing from the capital markets, or short-term borrowings from
    Thermo Electron, although there is no agreement with Thermo Electron to
    ensure that funds will be available on acceptable terms or at all.




                                       12PAGE
<PAGE>
                         THERMO INSTRUMENT SYSTEMS INC.

    PART II - OTHER INFORMATION

    Item 6 - Exhibits and Reports on Form 8-K

    (a) Exhibits

        See Exhibit Index on the page immediately preceding exhibits.

    (b) Reports on Form 8-K

        On January 22, 1997, the Company filed a Current Report on Form 8-K
    pertaining to its tender offer for all of the outstanding shares of Life
    Sciences International PLC.

        On April 4, 1997, the Company filed a Current Report on Form 8-K
    pertaining to its acquisition of Life Sciences International PLC.



















                                       13PAGE
<PAGE>
                         THERMO INSTRUMENT SYSTEMS INC.

                                   SIGNATURES


        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 as of the 6th day of May 1997.


                                         THERMO INSTRUMENT SYSTEMS INC.



                                         Paul F. Kelleher
                                         ----------------------------
                                         Paul F. Kelleher
                                         Chief Accounting Officer



                                         John N. Hatsopoulos
                                         ----------------------------
                                         John N. Hatsopoulos
                                         Vice President and Chief
                                           Financial Officer













                                       14PAGE
<PAGE>
                         THERMO INSTRUMENT SYSTEMS INC.

                                  EXHIBIT INDEX


    Exhibit
    Number        Description of Exhibit
    ------------------------------------------------------------------------

     10.1         $210,000,000 Promissory Note dated as of March 27, 1997,
                  issued by the Company to Thermo Electron Corporation.

     11           Statement re: Computation of Earnings per Share.

     27           Financial Data Schedule.