<PAGE>
                       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 April 4, 1998.

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

                         Commission File Number 1-12179

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

    Delaware                                                       85-0429899
    (State or other jurisdiction of                          (I.R.S. Employer
    incorporation or organization)                        Identification No.)

    504 Airport Road
    Santa Fe, New Mexico                                           87504-2108
    (Address of principal executive offices)                       (Zip Code)

       Registrant's telephone number, including area code: (781) 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 May 1, 1998
         ----------------------------        --------------------------
         Common Stock, $.01 par value           11,085,918 actual
                                                14,093,848 pro forma
PAGE
<PAGE>
    PART I - FINANCIAL INFORMATION

    Item 1 - Financial Statements
    -----------------------------

                         THERMO BIOANALYSIS CORPORATION

                           Consolidated Balance Sheet
                                   (Unaudited)

                                     Assets


                                                     April 4,     January 3,
    (In thousands)                                       1998           1998
    ------------------------------------------------------------------------
    Current Assets:
      Cash and cash equivalents (includes $13,012
        and $10,158 under repurchase agreement with
        affiliated company)                          $ 43,526       $ 39,704
      Accounts receivable, less allowances of
        $5,926 and $6,232                              45,146         47,210
      Inventories:
        Raw materials and supplies                     13,608         12,818
        Work in process                                 3,433          3,238
        Finished goods                                 22,241         22,579
      Prepaid income taxes                              8,475          8,484
      Prepaid expenses and other current assets         5,446          4,221
                                                     --------       --------
                                                      141,875        138,254
                                                     --------       --------

    Property, Plant, and Equipment, at Cost            35,274         34,405
      Less: Accumulated depreciation and
            amortization                               13,114         11,438
                                                     --------       --------
                                                       22,160         22,967
                                                     --------       --------
    Other Assets                                        2,397          2,712
                                                     --------       --------
    Cost in Excess of Net Assets of Acquired
      Companies                                       158,434        158,506
                                                     --------       --------
                                                     $324,866       $322,439
                                                     ========       ========

                                        2PAGE
<PAGE>
                         THERMO BIOANALYSIS CORPORATION

                     Consolidated Balance Sheet (continued)
                                   (Unaudited)

                    Liabilities and Shareholders' Investment


                                                      April 4,   January 3,
    (In thousands except share amounts)                   1998         1998
    -----------------------------------------------------------------------
    Current Liabilities:
      Borrowings under overdraft facility             $  3,190     $  2,465
      Accounts payable                                  12,618       12,596
      Accrued payroll and employee benefits              6,504        8,482
      Accrued income taxes                               5,550        6,097
      Accrued acquisition expenses (Note 2)              4,198        5,110
      Other accrued expenses                            13,651       13,482
      Deferred revenue                                   4,821        3,675
      Due to parent company and affiliated companies   
        (Note 2)                                        38,371       35,846
                                                      --------     --------
                                                        88,903       87,753
                                                      --------     --------
    Deferred Income Taxes                                  139          139
                                                      --------     --------
    Long-term Obligations:
      Note payable to parent company                    50,000       50,000
      Subordinated convertible note, due to parent
        company                                         50,000       50,000
      Other                                                198          204
                                                      --------     --------
                                                       100,198      100,204
                                                      --------     --------
    Shareholders' Investment:
      Common stock, $.01 par value, 25,000,000
        shares authorized; 14,091,470 and 14,081,448
        shares issued                                      141          141
      Capital in excess of par value                   131,585      131,483
      Retained earnings (Note 2)                        11,788        9,633
      Treasury stock at cost, 392 shares in 1998            (7)           -
      Accumulated other comprehensive items (Note 3)    (7,881)      (6,914)
                                                      --------     --------
                                                       135,626      134,343
                                                      --------     --------
                                                      $324,866     $322,439
                                                      ========     ========


    The accompanying notes are an integral part of these consolidated
    financial statements.
                                        3PAGE
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                         THERMO BIOANALYSIS CORPORATION

                        Consolidated Statement of Income
                                   (Unaudited)


                                                       Three Months Ended
                                                     ----------------------
                                                     April 4,     March 29,
    (In thousands except per share amounts)              1998          1997
    -----------------------------------------------------------------------
    Revenues                                          $54,434       $26,801
                                                      -------       -------
    Costs and Operating Expenses:
      Cost of revenues                                 26,583        13,848
      Selling, general, and administrative expenses    17,899         7,985
      Research and development expenses                 3,923         2,352
                                                      -------       -------
                                                       48,405        24,185
                                                      -------       -------
    Operating Income                                    6,029         2,616

    Interest Income                                       998           725
    Interest Expense (includes $1,865 and $771 to
      related party)                                   (2,003)         (856)
                                                      -------       -------
    Income Before Provision for Income Taxes            5,024         2,485
    Provision for Income Taxes                          1,822           903
                                                      -------       -------
    Net Income                                        $ 3,202       $ 1,582
                                                      =======       =======
    Earnings per Share (Note 4):
      Basic                                           $   .23       $   .15
                                                      =======       =======
      Diluted                                         $   .21       $   .14
                                                      =======       =======
    Weighted Average Shares (Note 4):
      Basic                                            14,086        10,624
                                                      =======       =======
      Diluted                                          17,299        13,694
                                                      =======       =======


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


                                        4PAGE
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                         THERMO BIOANALYSIS CORPORATION

                      Consolidated Statement of Cash Flows
                                   (Unaudited)


                                                        Three Months Ended
                                                      ----------------------
                                                      April 4,     March 29,
    (In thousands)                                        1998          1997
    ------------------------------------------------------------------------
    Operating Activities:
      Net income                                      $  3,202      $  1,582
      Adjustments to reconcile net income to net
        cash provided by (used in) operating 
        activities:
          Depreciation and amortization                  2,760         1,178
          Provision for losses on accounts
            receivable                                       5            10
          Changes in current accounts, excluding
            the effects of acquisitions:
              Accounts receivable                        2,062         2,749
              Inventories                               (1,407)       (3,370)
              Other current assets                      (1,136)       (2,179)
              Accounts payable                              29           450
              Other current liabilities                 (9,614)        1,070
                                                      --------      --------
    Net cash provided by (used in) operating 
      activities                                        (4,099)        1,490
                                                      --------      --------
    Investing Activities:
      Cash acquired through acquisitions                     -        23,995
      Adjustment to acquisition purchase price           9,075             -
      Purchases of property, plant, and equipment       (1,851)         (468)
      Other                                                220             -
                                                      --------      --------
    Net cash provided by investing activities            7,444        23,527
                                                      --------      --------

    Financing Activities:
      Net proceeds from issuance of Company common
        stock                                               95             -
      Repayment of long-term debt                            -          (240)
      Increase in bank overdraft facility                  725           219
                                                      --------      --------
    Net cash provided by (used in) financing 
      activities                                      $    820      $    (21)
                                                      --------      --------

                                        5PAGE
<PAGE>
                         THERMO BIOANALYSIS CORPORATION

                Consolidated Statement of Cash Flows (continued)
                                   (Unaudited)


                                                       Three Months Ended
                                                    ------------------------
                                                    April 4,       March 29,
    (In thousands)                                      1998            1997
    ------------------------------------------------------------------------
    Exchange Rate Effect on Cash                    $   (343)       $    732
                                                    --------        --------

    Increase in Cash and Cash Equivalents              3,822          25,728
    Cash and Cash Equivalents at Beginning of
      Period                                          39,704          45,476
                                                    --------        --------
    Cash and Cash Equivalents at End of Period      $ 43,526        $ 71,204
                                                    ========        ========

    Noncash Activities:
      Fair value of assets of acquired companies,
        including cash acquired of $23,995          $      -        $242,374
      Issuance of Company common stock for 
        acquired companies                                 -         (83,533)
      Promissory note payable to parent company
       for acquired companies                              -         (50,000)
      Debt payable to parent company for acquired
        companies                                          -         (78,914)
      Adjustments to purchase price due from parent
        company for acquired companies                     -           9,075
                                                    --------        --------
      Liabilities assumed of acquired companies     $      -        $ 39,002
                                                    ========        ========


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



                                        6PAGE
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                         THERMO BIOANALYSIS CORPORATION

                   Notes to Consolidated Financial Statements

    1.  General

        The interim consolidated financial statements presented have been
    prepared by Thermo BioAnalysis Corporation (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 April 4, 1998, the results of operations for the three-month periods
    ended April 4, 1998, and March 29, 1997, and the cash flows for the
    three-month periods ended April 4, 1998, and March 29, 1997. Interim
    results are not necessarily indicative of results for a full year.

        Historical financial results have been restated to include the
    Clinical Products Group of Life Sciences International (LSI), which was
    acquired in a transaction accounted for in a manner similar to a pooling
    of interests (Note 2). 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 Form S-1 filed with the Securities and Exchange
    Commission in May 1998.

    2.  Acquisitions

        In March 1997, Thermo Instrument Systems Inc. acquired approximately
    95% of the outstanding shares of LSI, a London Stock Exchange-listed
    company. Subsequently, Thermo Instrument acquired the remaining shares of
    LSI capital stock. In May 1998, the Company agreed to acquire the
    Clinical Products Group of LSI, which is comprised of Shandon Inc. and
    its related businesses, including ALKO Diagnostic Corporation, from
    Thermo Instrument. The Clinical Products Group provides equipment and
    consumables for cytology, histology, and pathology applications. It also
    supplies consumables for blood gas and ion-selective electrolyte
    analyzers. The net purchase price for the Clinical Products Group is
    approximately $66.7 million, which represents the sum of the net book
    value of the businesses as of April 4, 1998, plus a percentage of Thermo
    Instrument's total cost in excess of net assets acquired associated with
    its acquisition of LSI, based on the 1996 revenues of the Clinical
    Products Group relative to LSI's 1996 consolidated revenues. The Company
    believes that this allocation methodology is reasonable and in accordance
    with the guidance provided by Staff Accounting Bulletin 55 (Topic 1:B).

         The net purchase price for the Clinical Products Group will be paid
    with 3,007,930 shares of Company common stock valued at $22.16 per share,
    representing the five-day average for the period preceding the date the
    parties reached agreement in principle on the material terms of the
    transaction. Issuance of the common stock to Thermo Instrument will occur
    immediately after the listing upon the American Stock Exchange of the
    3,007,930 shares of Company common stock, which will require approval by
    the Company's shareholders. Because Thermo Instrument is the Company's
    majority shareholder and intends to vote its shares in favor of such

                                        7PAGE
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                         THERMO BIOANALYSIS CORPORATION

    2.  Acquisitions (continued)

    listing, the approval is assured. In addition to the shares of Company
    common stock to be issued to Thermo Instrument, the Company will assume
    approximately $37.9 million of existing indebtedness owed by the Clinical
    Products Group to Thermo Instrument, making the gross purchase price
    approximately $104.5 million. This amount includes approximately $12.0
    million for an equivalent amount of cash acquired. The existing
    indebtedness owed to Thermo Instrument is due January 2, 1999, and bears
    interest at the 90-day Commercial Paper Composite Rate plus 25 basis
    points, set at the beginning of each quarter.

        Because the Company and the Clinical Products Group of LSI were
    deemed for accounting purposes to be under control of their common
    majority owner, Thermo Instrument, the transaction has been accounted for
    in a manner similar to a pooling of interests. Accordingly, the
    accompanying financial statements include the results of the Clinical
    Products Group of LSI from March 12, 1997, the date these businesses were
    acquired by Thermo Instrument, and the 3,007,930 shares issuable to
    Thermo Instrument have been deemed outstanding from that date and are
    therefore included in the computation of earnings per share. The purchase
    price for the Clinical Products Group of LSI included $4.5 million for
    the increase in net book value from the date the Clinical Products Group
    of LSI was acquired by Thermo Instrument (including $1.1 million for
    earnings during the first quarter of 1998). This amount was recorded as a
    deemed distribution from retained earnings, reflecting consideration to
    Thermo Instrument for the earnings of the Clinical Products Group from
    the date of the acquisition by Thermo Instrument.

        In connection with the acquisitions of the Clinical Products Group of
    LSI and the Labsystems OY and Hybaid divisions of LSI, the Company is in
    the process of restructuring the acquired businesses. This restructuring
    is expected to primarily include reductions in staffing levels and, to a
    lesser extent, costs for termination of certain joint venture
    arrangements. In accordance with the requirements of EITF 95-3, as part
    of the cost of the acquisition, the Company has established reserves of
    approximately $8,536,000, of which the Company expended $3,426,000 during
    1997 and $912,000 in the first quarter of 1998, primarily for severance
    payments. Unresolved matters at April 4, 1998, included completing
    planned severances and termination of joint ventures. Finalization of the
    Company's plan for restructuring the acquired businesses occurred during
    the first quarter of 1998.

        Following a vote of the Company's shareholders in April 1998, the
    Company issued to Thermo Instrument 1,300,000 shares of its common stock
    to complete its 1997 acquisition of the Labsystems OY and Hybaid
    divisions of LSI.

                                        8PAGE
<PAGE>
                         THERMO BIOANALYSIS CORPORATION

    3.  Comprehensive Income

        During the first quarter of 1998, the Company adopted Statement of
    Financial Accounting Standards No. 130, "Reporting Comprehensive Income."
    This pronouncement sets forth requirements for disclosure of the
    Company's comprehensive income and accumulated other comprehensive items.
    In general, comprehensive income combines net income and "other
    comprehensive items" which represent foreign currency translation
    adjustments, reported as a component of shareholders' investment in the
    accompanying balance sheet. During the first quarter of 1998 and 1997,
    the Company had comprehensive income of $2,235,000 and $1,823,000,
    respectively.

    4.  Earnings per Share 

        Basic and diluted earnings per share were calculated as follows:

                                                        Three Months Ended
                                                       --------------------
                                                       April 4,   March 29,
    (In thousands except per share amounts)                1998        1997
    -----------------------------------------------------------------------
    Basic
    Net income                                          $ 3,202     $ 1,582
                                                        -------     -------
    Weighted average shares                              11,078      10,029
    Shares issuable for acquisition of Clinical 
      Products Group of LSI (Note 2)                      3,008         595
                                                        -------     -------
    Weighted average shares, as adjusted                 14,086      10,624
                                                        -------     -------
    Basic earnings per share                            $   .23     $   .15
                                                        =======     =======
    Diluted
    Net income                                          $ 3,202     $ 1,582
    Effect of convertible debentures                        390         390
                                                        -------     -------
    Income available to common shareholders,
      as adjusted                                       $ 3,592     $ 1,972
                                                        -------     -------
    Basic weighted average shares                        14,086      10,624
    Effect of:
      Convertible debentures                              3,030       3,030  
      Stock options                                         183          40
                                                        -------     -------
    Weighted average shares, as adjusted                 17,299      13,694
                                                        -------     -------
    Diluted earnings per share                          $   .21     $   .14
                                                        =======     =======

                                        9PAGE
<PAGE>
                         THERMO BIOANALYSIS CORPORATION

    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 "Risk Factors" included in the
    Company's Registration Statement on Form S-1 (Reg. No. 333-52445).

    Overview

        The Company has three principal product lines: biomolecular
    instruments and consumables, clinical laboratory equipment and supplies,
    and information management systems. The Company's biomolecular
    instruments and consumables are based on proprietary immunoassay, optical
    biosensor, polymerase chain reaction (PCR), MALDI-TOF mass spectometry
    (MALDI-TOF), DNA amplification and capillary electrophoresis (CE)
    technologies, and are used in pharmaceutical and biopharmaceutical
    research, as well as for clinical laboratory testing and diagnosis of
    patient samples. The Company's clinical laboratory business supplies a
    range of equipment and consumables with applications in cytology,
    histology, and pathology. The Company's information management systems
    business designs, implements, and supports laboratory information
    management systems (LIMS), and chromatography data systems (CDS) for use
    in laboratories, industrial applications, and clinical testing
    facilities.

         The Company was incorporated in February 1995 and on February 7,
    1996, acquired the Dynex Technologies division of Dynatech Corporation.
    Since then, the Company has acquired from Thermo Instrument the
    LabSystems and Affinity Sensors divisions of Fisons, the Labsystems OY,
    Hybaid and Labsystems Japan divisions of LSI, and the Clinical Products
    Group of LSI. The Company's financial statements include the results of
    operations of the acquired divisions of Fisons and LSI from March 29,
    1996 and March 12, 1997, respectively, the date these businesses were
    acquired by Thermo Instrument (Note 2).

         In July 1998, the Company will contribute the assets and liabilities
    of its health physics division to a joint venture the Company is forming
    with Thermo Instrument. The Company will receive a 49% equity interest in
    the joint venture, and will initially receive 67% of the profit and
    losses of the joint venture. The Company's health physics business had
    revenues of $13.4 million in 1997.

         A significant percentage of the Company's revenues are derived from
    sales of products and services outside the U.S., including certain Asian
    countries, through export sales and sales by the Company's foreign 

                                       10PAGE
<PAGE>
                         THERMO BIOANALYSIS CORPORATION

    Overview (continued)

    operations. Asia is experiencing a severe economic crisis, which has been
    characterized by sharply reduced economic activity and liquidity, highly
    volatile foreign-currency-exchange and interest rates, and unstable stock
    markets. The Company's sales to Asia could be adversely affected by the
    unstable economic conditions there. 

         The Company anticipates that a significant portion of its revenues
    will continue to be from sales to customers outside the U.S. As a result,
    the Company's financial performance and competitive position can be
    affected by currency exchange rate fluctuations. The Company may use
    forward contracts to reduce its exposure to currency fluctuations.

    Results of Operations

    First Quarter 1998 Compared With First Quarter 1997
    ---------------------------------------------------

        Revenues increased to $54.4 million in the first quarter of 1998 from
    $26.8 million in the first quarter of 1997. Revenues increased $28.0
    million due to acquisitions (Note 2). In addition, an increase in
    revenues at Dynex was slightly more than offset by decreases in sales of
    LIMS and MALDI-TOF instruments. Revenues also decreased $0.2 million due
    to the strengthening of the U.S. dollar relative to foreign currencies in
    countries where the Company operates.

        The gross profit margin increased to 51% in the first quarter of 1998
    from 48% in the first quarter of 1997, primarily due to the inclusion of
    a full period of higher-margin revenues from the Labsystems OY
    liquid-handling business, acquired effective March 12, 1997, as well as
    an increase in the gross profit margin at Dynex, primarily due to an
    increase in the sale of certain higher-margin products. These increases
    were offset in part by inclusion of a full period of lower-margin
    revenues from the clinical laboratory products business, acquired
    effective March 12, 1997.

        Selling, general, and administrative expenses as a percentage of
    revenues increased to 33% in the first quarter of 1998 from 30% in the
    first quarter of 1997, primarily due to the inclusion of the liquid
    handling and PCR businesses, which have higher costs as a percentage of
    revenues, for a full period in 1998, offset in part by the impact of the
    inclusion of the clinical laboratory products business, which has lower
    costs as a percentage of revenues, for a full period in 1998. Research
    and development expenses increased to $3.9 million in the first quarter
    of 1998 from $2.4 million in the first quarter of 1997, primarily due to
    the inclusion of a full period of expenses at acquired businesses.
    Research and development expenses as a percentage of revenues decreased
    to 7% in 1998 from 9% in 1997, primarily due to lower costs as a
    percentage of revenues at acquired businesses.

        Interest income increased to $1.0 million in the first quarter of
    1998 from $0.7 million in the first quarter of 1997, primarily due to
    interest income received from Thermo Instrument on a $9.1 million
    adjustment to the aggregate purchase price for the acquisitions of the 

                                       11PAGE
<PAGE>
                         THERMO BIOANALYSIS CORPORATION

    First Quarter 1998 Compared With First Quarter 1997 (continued)
    ---------------------------------------------------

    Labsystems OY, Hybaid, and Labsystems Japan divisions of LSI, offset in
    part by the effect of lower average invested balances in 1998. Interest
    expense increased to $2.0 million in the first quarter of 1998 from $0.9
    million in the first quarter of 1997, primarily due to interest expense
    on the debt to Thermo Instrument associated with the Company's
    acquisitions. 

         The effective tax rate was 36% in both periods, and exceeded the
    statutory federal income tax rate primarily due to the impact of state
    income taxes and nondeductible amortization of cost in excess of net
    assets of acquired companies, offset in part by the impact of relatively
    low tax rates in certain countries in which the Company operates.

    Liquidity and Capital Resources

        Consolidated working capital was $53.0 million as of April 4, 1998,
    compared with $50.5 million as of January 3, 1998. Included in working
    capital are cash and cash equivalents of $43.5 million as of April 4,
    1998, compared with $39.7 million as of January 3, 1998. Of the Company's
    total cash and cash equivalents at April 4, 1998, $13.0 million was
    invested in a repurchase agreement with Thermo Electron Corporation.
    During the first quarter of 1998, operating activities used $4.1 million
    of cash. A decrease in other current liabilities used $9.6 million in
    cash, primarily due to the repayment of certain trade and other operating
    balances payable to other Thermo Instrument companies.

        The Company's investing activities provided $7.4 million in cash in
    the first quarter of 1998. The Company made expenditures of $1.9 million
    for purchases of property, plant, and equipment, and expects to make
    capital expenditures of approximately $4.9 million during the remainder
    of 1998. During the first quarter of 1998, the Company received purchase
    price adjustments aggregating $9.1 million from Thermo Instrument,
    related to the acquisitions of the Labsystems OY, Hybaid, and Labsystems
    Japan divisions of LSI.

        In May 1998, the Company agreed to acquire the Clinical Products
    Group of LSI from Thermo Instrument (Note 2). The net purchase price of
    $66.7 million will be paid with 3,007,930 shares of Company common stock.
    In addition, the Company has assumed approximately $37.9 million of
    existing indebtedness owed by the Clinical Products Group of LSI to
    Thermo Instrument, making the gross purchase price approximately $104.5
    million. This amount includes approximately $12.0 million for an
    equivalent amount of cash acquired. The existing indebtedness owed to
    Thermo Instrument is due January 2, 1999, and bears interest at the
    90-day Commercial Paper Composite Rate plus 25 basis points, set at the
    beginning of each quarter.

         The Company has undertaken a restructuring of certain acquired
    businesses (Note 2). Amounts accrued for such activities total $4.2
    million at April 4, 1998. The payments will primarily occur during the
    remainder of 1998. The Company expects that such expenditures will not
    change materially from amounts accrued at April 4, 1998.

                                       12PAGE
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                         THERMO BIOANALYSIS CORPORATION

    Liquidity and Capital Resources (continued)

        The Company's financing activities provided $0.8 million of cash
    during the first quarter of 1998. A net increase in the Company's bank
    overdraft facility provided $0.7 million.

        The Company has signed one agreement and two non-binding letters of
    intent relating to the purchase of three businesses for aggregate
    consideration of approximately $16.1 million in cash. These proposed
    acquisitions are subject to certain conditions, including, in the case of
    the agreement, stockholder approval by the potential acquiree, and in the
    case of the non-binding letters of intent, completion of due diligence
    and negotiation of definitive agreements. There can be no assurance that
    these acquisitions will be completed.

        In May 1998, the Company filed a registration statement under the
    Securities Act of 1933 with the Securities and Exchange Commission for a
    public offering of 4,500,000 shares of common stock. In addition, the
    underwriters are expected to be granted a 30-day over-allotment option to
    purchase up to an additional 675,000 shares of common stock. There can be
    no assurance that such offering will be completed.

        Although the Company expects to have positive cash flow from its
    existing operations, the Company anticipates it will require significant
    amounts of cash for the possible acquisition of complementary businesses
    and technologies. The Company expects that it will finance these
    acquisitions through a combination of internal funds, additional debt or
    equity financing and/or short-term borrowings from Thermo Instrument or
    Thermo Electron, although there is no agreement with these companies to
    ensure that funds will be available on acceptable terms or at all. If the
    offering of common stock described above is completed, the Company
    expects to repay its $37.9 million debt payable to Thermo Instrument with
    a portion of such net proceeds. The Company also has a $50.0 million
    promissory note payable to Thermo Instrument due in July 1999, which it
    expects to repay through a combination of internal funds and additional
    debt or equity financing, possibly to include a portion of the net
    proceeds from the sale of the shares of common stock described above.
    Thermo Instrument, however, has stated its intention to require repayment
    of such indebtedness only to the extent that the Company's resources
    permit. Accordingly, the Company believes that its existing cash and cash
    equivalents are sufficient to meet the capital requirements of its
    existing businesses for the foreseeable future.

    PART II - OTHER INFORMATION
    ---------------------------

    Item 4 - Submission of Matters to a Vote of Security Holders
    ------------------------------------------------------------

        On April 2, 1998, at a Special Meeting of Stockholders, the Company's
    stockholders approved the listing of 1,300,000 shares of the Company's
    common stock on the American Stock Exchange, in connection with the
    Company's 1997 acquisition of the Labsystems OY and Hybaid divisions of
    LSI. Of the total votes, 8,325,521 shares were voted in favor of the
    proposal, 2,516 shares were voted against the proposal, and 1,200 shares
    abstained. No broker nonvotes were recorded.

                                       13PAGE
<PAGE>
                         THERMO BIOANALYSIS CORPORATION

    Item 6 - Exhibits
    -----------------

        See Exhibit Index on the page immediately preceding exhibits.














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                         THERMO BIOANALYSIS CORPORATION

                                   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 19th day of May 1998.

                                        THERMO BIOANALYSIS CORPORATION



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



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










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                         THERMO BIOANALYSIS CORPORATION

                                  EXHIBIT INDEX


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

      2.4       Share Purchase Agreement dated as of May 11, 1998, between   
                the Company and Thermo Instrument Systems Inc. (incorporated
                by reference herein from Exhibit 2.4 to the Company's   
                Registration Statement on Form S-1 [Reg. No. 333-52445]).

      2.5       Share Purchase Agreement dated as of May 11, 1998, between 
                the Company and ThermoQuest Corporation (incorporated by
                reference herein from Exhibit 2.5 to the Company's
                Registration Statement on Form S-1 [Reg. No. 333-52445]).

    10.21       $50,000,000 Principal Amount Promissory Note, due 1999,
                dated April 30, 1998 (incorporated by reference herein from
                Exhibit 10.21 to the Company's Registration Statement on
                Form S-1 [Reg. No. 333-52445]).  

       27        Financial Data Schedule.
     


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