<PAGE>   1
                     U.S. SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 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 quarterly period ended July 3, 1999 or

[ ]  Transition report pursuant to Section 13 or 15(d) of the Securities
     Exchange Act of 1934 for the transition period from __________
     to ___________


COMMISSION FILE NUMBER:  1-8145


                        THORATEC LABORATORIES CORPORATION
        ----------------------------------------------------------------
        (Exact Name of Small Business Issuer as Specified in Its Charter)

<TABLE>
<S>                                                                  <C>
               California                                               94-2340464
------------------------------------------------                    -------------------
(State or Other Jurisdiction of Incorporation or                    (I.R.S. Employer
              Organization)                                         Identification No.)
</TABLE>

               6035 Stoneridge Drive, Pleasanton, California 94588
             ------------------------------------------------------
               (Address of Principal Executive Offices) (Zip Code)



Registrant's telephone number, including area code:  (925) 847-8600



     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 / /



     As of July 19, 1999 registrant had 20,443,145 shares of common stock
outstanding.



<PAGE>   2

                          PART I. FINANCIAL INFORMATION

ITEM 1.  FINANCIAL STATEMENTS

                THORATEC LABORATORIES CORPORATION AND SUBSIDIARY

                      CONDENSED CONSOLIDATED BALANCE SHEETS
                                   (Unaudited)

<TABLE>
<CAPTION>
                                                              July 3, 1999       January 2, 1999
                                                             ---------------    ------------------
<S>                                                           <C>                <C>
ASSETS
Current Assets:
Cash and cash equivalents ..............................      $  2,078,431       $  2,712,686
Short-term investments available-for-sale ..............         2,093,480          2,032,107
Receivables ............................................         3,923,520          4,141,854
Inventories (Note 3) ...................................         6,533,418          5,290,745
Prepaid expenses and other .............................           183,230            404,737
                                                              ------------       ------------
Total Current Assets ...................................        14,812,079         14,582,129
Equipment and improvements, at cost ....................        11,646,355         12,460,755
Accumulated depreciation and amortization ..............        (2,112,371)        (2,835,365)
                                                              ------------       ------------
Equipment and leasehold improvements - net .............         9,533,984          9,625,390
Other Assets ...........................................         1,018,296          1,000,898
                                                              ------------       ------------
TOTAL ASSETS ...........................................      $ 25,364,359       $ 25,208,417
                                                              ============       ============

LIABILITIES AND SHAREHOLDERS' EQUITY
Current Liabilities:
Accounts payable .......................................      $  1,211,514       $  1,307,768
Accrued compensation ...................................         1,103,140          1,613,334
Product sales advances .................................           108,524            121,373
Deferred distributor revenue (Note 5) ..................           284,765
Other ..................................................           357,335            288,585
                                                              ------------       ------------
Total Current Liabilities ..............................         3,065,278          3,331,060
Commitments
Long term deferred distributor revenue (Note 5)                    996,676
                                                              ------------       ------------
Total liabilities ......................................         4,061,954          3,331,060
                                                              ------------       ------------
Shareholders' Equity:
Common shares, 100,000,000 authorized;
   issued and outstanding 20,438,865 in 1999
   and 20,422,952 in 1998 ..............................        72,855,926         72,810,450
Paid-in capital ........................................         2,482,229          2,482,229
Accumulated deficit ....................................       (53,790,617)       (53,402,106)
Other comprehensive loss:
Unrealized loss on investments - net ...................            (2,530)                 8
Cumulative translation adjustments .....................          (242,603)           (13,224)
                                                              ------------       ------------
Total other comprehensive loss..........................          (245,133)           (13,216)
                                                              ------------       ------------
Total Shareholders' Equity .............................        21,302,405         21,877,357
                                                              ------------       ------------
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY .............      $ 25,364,359       $ 25,208,417
                                                              ============       ============
</TABLE>

See notes to condensed consolidated financial statements



                                        2
<PAGE>   3

           THORATEC LABORATORIES CORPORATION AND SUBSIDIARY CONDENSED

                      CONSOLIDATED STATEMENTS OF OPERATIONS
                                   (Unaudited)


<TABLE>
<CAPTION>
                                                      Three Months Ended                    Six Months Ended
                                                --------------------------------      -------------------------------
                                                  July 3,            July 4,            July 3,            July 4,
                                                    1999               1998               1999               1998
                                                -------------      -------------      ------------       ------------
<S>                                             <C>                <C>                <C>                <C>
Revenue:
  Product sales - net ....................      $  4,891,678       $  4,208,396       $ 10,267,151       $  7,711,460
  Interest and other income ..............           201,952            195,568            372,228            395,413
                                                ------------       ------------       ------------       ------------

  Total revenue ..........................         5,093,630          4,403,964         10,639,379          8,106,873
                                                ------------       ------------       ------------       ------------

Costs and expenses:
  Costs of products sold .................         1,661,166          1,621,111          4,008,764          2,977,703
  Research and development ...............         1,277,850          1,265,434          2,431,075          2,485,494
  Selling, general and administrative ....         2,207,514          2,087,517          4,588,052          3,887,984
                                                ------------       ------------       ------------       ------------
  Total costs and expenses ...............         5,146,530          4,974,062         11,027,891          9,351,181
                                                ------------       ------------       ------------       ------------

Net loss .................................      $    (52,900)      $   (570,098)      $   (388,512)      $ (1,244,308)
                                                ============       ============       ============       ============


 Basic and diluted loss per share (Note 4)      $      (0.00)      $      (0.03)      $      (0.02)      $      (0.06)
                                                ============       ============       ============       ============

  Shares used to compute basic and
     diluted loss per share ..............        20,437,158         20,322,322         20,431,584         20,303,778
</TABLE>


See notes to condensed consolidated financial statements.



                                        3
<PAGE>   4

           THORATEC LABORATORIES CORPORATION AND SUBSIDIARY CONDENSED

                  CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS
                                   (Unaudited)


<TABLE>
<CAPTION>
                                                       Three Months Ended                   Six Months Ended
                                                 -----------------------------       -----------------------------
                                                   July 3,          July 4,           July 3,          July 4,
                                                     1999             1998              1999             1998
                                                 -----------       -----------       -----------       -----------
<S>                                              <C>               <C>               <C>               <C>
Net loss ..................................      $   (52,900)      $  (570,098)      $  (388,512)      $(1,244,308)
Other net comprehensive income:
   Unrealized gain (loss) on securities ...           (1,618)              335            (2,538)            6,837
   Foreign currency translation adjustments          (36,400)          (16,398)         (229,379)            7,342
                                                 -----------       -----------       -----------       -----------
Other comprehensive income (loss) .........          (38,018)          (16,063)         (231,917)           14,179
                                                 -----------       -----------       -----------       -----------
Comprehensive loss ........................      $   (90,918)      $  (586,161)      $  (620,429)      $(1,230,129)
                                                 ===========       ===========       ===========       ===========
</TABLE>



                                        4
<PAGE>   5

                THORATEC LABORATORIES CORPORATION AND SUBSIDIARY

                 CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
                                   (Unaudited)

<TABLE>
<CAPTION>
                                                                         Six Months Ended
                                                                 ----------------------------------
                                                                  July 3, 1999       July 4, 1998
                                                                 ---------------   ----------------
<S>                                                              <C>               <C>
Cash flows from operating activities:
  Net loss ................................................      $  (388,512)      $(1,244,308)
  Adjustments to reconcile net loss to net cash used in
  operating activities:
    Amortization of deferred distributor revenue ..........         (142,382)
    Depreciation and amortization .........................          468,290           319,924
    Loss on sale of asset .................................            2,034
    Changes in assets and liabilities:
      Receivables .........................................          209,465        (1,319,910)
      Prepaid expenses and other ..........................          218,931           105,907
      Inventories .........................................       (1,294,693)       (1,510,944)
      Other Assets ........................................          (17,611)          (27,327)
      Accounts payable and other liabilities ..............         (625,557)          576,812
      Deferred distributor revenue ........................        1,423,823
                                                                 -----------       -----------

Net cash used in operating activities .....................         (146,212)       (3,099,846)
                                                                 -----------       -----------

Cash flows from investing activities:
  Purchases of short-term investments available-for-sale ..       (5,101,483)       (8,148,285)
  Maturities of short-term investments available-for-sale .        4,224,000         7,875,000
  Sales of short-term investments available-for-sale.......          813,572           141,271
  Capital expenditures ....................................         (434,784)       (3,225,224)
                                                                 -----------       -----------

    Net cash provided by (used in) investing activities ...         (498,695)       (3,357,238)
                                                                 -----------       -----------

Cash flows from financing activities:
  Common stock issued upon exercise of options ............           45,476            66,482
                                                                 -----------       -----------

  Net cash provided by financing activities ...............           45,476            66,482
                                                                 -----------       -----------

Effect of exchange rate changes on cash ...................          (34,824)           (1,008)
                                                                 -----------       -----------

Net increase (decrease) in cash and cash equivalents ......         (634,255)       (6,391,610)

Cash and cash equivalents at beginning of period ..........        2,712,686         9,469,311
                                                                 -----------       -----------

Cash and cash equivalents at end of period ................      $ 2,078,431       $ 3,077,701
                                                                 ===========       ===========

Noncash Financing Transaction:
  Construction costs and capital assets in accounts payable      $    42,139       $ 1,811,661
</TABLE>


See notes to condensed consolidated financial statements.



                                        5
<PAGE>   6

                THORATEC LABORATORIES CORPORATION AND SUBSIDIARY

              NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
                                   (Unaudited)


1.  BASIS OF PRESENTATION

    The interim consolidated financial statements presented have been prepared
    by Thoratec Laboratories Corporation (the Company) without audit and, in the
    opinion of management, reflect all adjustments necessary (consisting only of
    normal recurring adjustments) to present fairly the financial position,
    results of operations and cash flows at July 3, 1999 and for all periods
    presented. The results of operations for any interim period are not
    necessarily indicative of results for a full year.

    The consolidated balance sheet presented as of January 2, 1999, 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 the Securities and
    Exchange Commission and do not contain certain information included in the
    annual consolidated financial statements and notes of the Company. It is
    suggested that the accompanying condensed consolidated financial statements
    be read in conjunction with the audited consolidated financial statements
    and the notes thereto contained in the Company's Annual Report on Form 10-K
    for the fiscal year ended January 2, 1999, filed with the Securities and
    Exchange Commission.

    The preparation of the Company's consolidated financial statements in
    conformity with generally accepted accounting principles necessarily
    requires management to make estimates and assumptions that affect the
    reported amounts of assets and liabilities and disclosure of contingent
    assets and liabilities at the consolidated balance sheet dates and the
    reported amounts of revenues and expenses for the periods presented.

    Certain reclassifications have been made to the 1998 amounts to conform to
    the 1999 presentation.

2.  RECENTLY ISSUED ACCOUNTING STANDARD

    During June 1998, the Financial Accounting Standards Board (FASB) issued
    Statement of Financial Accounting Standards No. 133, "Accounting for
    Derivative Instruments and Hedging Activities", which defines derivatives,
    requires that all derivatives be carried at fair value, and provides for
    hedging accounting when certain conditions are met. Such Statement is
    effective for fiscal quarters beginning after June 15, 2000. The Company
    will evaluate the new standard to determine any required new disclosures.



                                        6
<PAGE>   7

3.  INVENTORIES

    Inventories consist of the following:

<TABLE>
<CAPTION>
                       July 3, 1999     January 2, 1999
                      --------------   -----------------
<S>                    <C>               <C>
Finished goods         $3,830,617        $2,712,543

Work in process         1,501,972         1,456,784

Raw materials           1,200,829         1,121,418
                       ----------        ----------

Total                  $6,533,418        $5,290,745
                       ==========        ==========
</TABLE>



4.  EARNINGS PER SHARE

    The Company calculates basic earnings per share (EPS) and diluted EPS in
    accordance with Statement of Financial Accounting Standards No. 128,
    "Earnings per Share" (SFAS 128). Basic EPS is computed by dividing net
    income (loss) for the period by the weighted average number of common shares
    outstanding for that period. Diluted EPS takes into account the effect of
    dilutive instruments, such as stock options, and uses the average share
    price for the period in determining the number of incremental shares that
    are to be added to the weighted average number of shares outstanding.
    Diluted EPS for the three months and six months ended July 3, 1999 and the
    three months and six months ended July 4, 1998 exclude any effect of such
    instruments because their inclusion would be antidilutive.

    The following is a summary of the calculation of the number of shares used
    in calculating basic and diluted EPS:

<TABLE>
<CAPTION>
                                            Three Months Ended              Six Months Ended
                                        --------------------------      --------------------------
                                         July 3,         July 4,         July 3,         July 4,
                                           1999            1998            1999            1998
                                        ----------     -----------      ----------      ----------
<S>                                     <C>             <C>             <C>             <C>
Shares used to compute basic EPS        20,437,158      20,322,322      20,431,584      20,303,778
Add: effect of dilutive securities              --              --              --              --
                                        ----------      ----------      ----------      ----------
Shares used to compute diluted EPS      20,437,158      20,322,322      20,431,584      20,303,778
                                        ==========      ==========      ==========      ==========
</TABLE>



                                        7
<PAGE>   8

5.  DISTRIBUTOR AGREEMENT

    During the first quarter of 1999, the Company entered into a five-year
    distribution agreement with Guidant Corporation. Under the terms of the
    agreement, Guidant receives exclusive worldwide marketing and distribution
    rights to the Thoratec Vectra(TM) Vascular Access Graft product line, except
    in Japan. In exchange for these rights, Guidant has paid Thoratec a
    non-refundable payment of $1.5 million, and will pay up to an additional $2
    million when the Vectra(TM) product line receives FDA approval for use in
    the U.S. Guidant also issued a four-year, unsecured line of credit in the
    amount of $10 million to Thoratec, which may be used, if needed, for a
    variety of business purposes. The Company will account for the $1.4 million
    (net of expenses) contract payment received in the first quarter of 1999 as
    revenue ratably over the five-year life of the contract. Other income in
    1999 included $71,000 and $142,000 of such payment amortization in the
    second quarter and six months, respectively. Current liabilities of $285,000
    and long-term liabilities of $997,000 are also reported as remaining
    balances as of July 3, 1999, since the Guidant payment will be amortized
    over twenty quarters.



                                        8
<PAGE>   9

ITEM 2.  MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL
         CONDITION AND RESULTS OF OPERATION

Liquidity and Capital Resources

At the end of the second quarter of 1999 the Company had working capital of
$11,747,000 compared with $11,251,000 at the end of 1998. The increase in
working capital was due to an increase in current assets, driven by an increase
in inventory partially offset by decreases in prepaid expenses and cash.
Inventories increased in preparation for planned increases in sales activity.
Cash was used to support ongoing operations as well as planned expenditures for
the Company's new manufacturing facility. Prepaid expenses decreased due to
amortization of insurance and property taxes. Additionally, current liabilities
decreased due to payment of commissions offset by an increase in deferred
distributor revenue. During the first quarter of 1999, the Company entered into
a five-year distribution agreement with Guidant Corporation under which Guidant
receives exclusive worldwide marketing and distribution rights to the Thoratec
Vectra(TM) Vascular Access Graft product line, except in Japan. In exchange for
these rights, Guidant has paid Thoratec a non-refundable payment of $1.5
million, and will pay up to an additional $2 million when the Vectra(TM) product
line receives FDA approval for use in the U.S. The Company received $1.4
million, net of expenses, in conjunction with this distribution agreement in the
first quarter of 1999. Since the payment will be amortized into revenue over
twenty quarters, $142,000 was recorded in other income in the first six months
of 1999. $285,000 of current and $997,000 of long-term deferred distributor
revenue liabilities were also reported as remaining balances in the first six
months of 1999. Guidant also issued a four-year, unsecured line of credit in the
amount of $10 million to Thoratec, which may be used, if needed, for a variety
of business purposes.

The Company believes it has sufficient funds to increase its marketing efforts,
to conduct clinical trials on its new products, and to develop new sources of
revenue, including new products, for at least the next year. The Company expects
that its operating expenses will increase in future periods as the Company
expends increased amounts on product manufacturing, marketing and research and
development of new product lines. The Company expects to break even in the
current year. However, there can be no assurance that the Company will achieve
profitability or positive cash flow.

The Company does not expect that inflation will have a material impact on its
operations.

Results of Operations

Fiscal Quarters Ended July 3, 1999 and July 4, 1998

Product sales in the second quarter of 1999 were approximately $4,892,000
compared to $4,208,000 in the second quarter of 1998. The $684,000, or 16%,
increase is due to increases in the number of domestic and international centers
using the VAD System as well as increases in the average selling price of the
VAD System domestically. Included in product sales is rental income in the
second quarter of 1999 of approximately $252,000 compared to $342,000 in the
second quarter of 1998. The $90,000, or 26%, decrease is principally due to new
and existing centers purchasing drivers rather than renting the equipment.
Interest and other income in the second quarter of 1999 was slightly higher when
compared to the second quarter of 1998. The increase was due to higher revenue
from the skeletal muscle project grant and $71,000 of revenue recognized in
other income as a result of the amortization of the $1.4 million Guidant payment
as described in the "Liquidity and Capital Resources" section above. These
increases were primarily offset by less interest income earned on lower cash
balances. Cost of sales increased $40,000 or 2%, in the second quarter of 1999.
Gross margin increased from 61% in the second quarter of 1998 to 66% in the
second quarter of 1999 due to changes in sales mix with increased unit sales of
VAD pumps worldwide, higher average selling prices for the VAD pumps and



                                        9
<PAGE>   10
reduced fixed overhead costs as a result of the completion of the transfer of
its manufacturing operations to the Company's new Pleasanton facility in May
1999. Research and development expenses for the second quarter of 1999 increased
$12,000, or 1%, compared to the second quarter of 1998 due principally to
increased expenses associated with the implantable VAD and Vectra(TM) projects
offset by decreases in costs associated with the TLC II(TM). Selling, general
and administrative expenses in the second quarter of 1999 increased $120,000, or
6%, compared to the second quarter of 1998 due to growth of sales and marketing
personnel and related costs and increased operating expenses related to the
Pleasanton facility.




Six Months Ended July 3, 1999 and July 4, 1998

Product  sales in the first six  months of 1999 were  approximately  $10,267,000
compared to $7,711,000 in the first six months of 1998.  The  $2,556,000 or 33%,
increase is due to increases in the number of domestic and international centers
using the VAD system,  as well as increases in the average  selling price of the
VAD System domestically. Included in product sales is rental income in the first
six months of 1999 of approximately  $577,000  compared to $617,000 in the first
six months of 1998.  The $40,000 or 6% decrease  is  principally  due to new and
existing centers purchasing drivers rather than renting the equipment.  Interest
and other  income in the first six months of 1999  decreased  to  $372,000  from
$395,000  due to lower  interest  income on  overall  lower cash  balances  from
operating uses and capital  expenditures  partially offset by increases from the
skeletal muscle project grant and $142,000 of revenue recognized in other income
as a result of the amortization of the $1.4 million Guidant payment as described
in the "Liquidity and Capital  Resources" section above. Cost of sales increased
$1,031,000, or 35%, in the first six months of 1999 as compared to the first six
months  of 1998 as a result  of  higher  sales in 1999,  non-recurring  expenses
associated  with the transfer of  manufacturing  operations to the Company's new
Pleasanton  facility  in the first  quarter  of 1999,  offset by  reduced  fixed
overhead  costs as a result of the  completion  of this  transfer  in the second
quarter of 1999. As a result,  gross margin remained  constant at 61%.  Research
and development  expenses for the first six months of 1999 decreased $54,000, or
2%,  compared to the first six months of 1998 due to the  completion  of the TLC
II(TM) project.  Research and  development  expenses are expected to increase in
future  quarters  due to higher  clinical  trial costs  associated  with the TLC
II(TM) , Vectra(TM) and Aria(TM) projects.  Selling,  general and administrative
expenses in the first six months of 1999 increased $700,000, or 18%, compared to
the first six months of 1998 due to growth of sales and marketing  personnel and
related  costs  and  increased  operating  expenses  related  to the  Pleasanton
facility.

OTHER MATTERS
The Year 2000 issue involves computer programs and embedded microprocessors in
computer systems and other equipment that utilize two digits rather than four to
define the applicable year. These systems may be programmed to assume that all
two-digit dates are preceded by "19", causing "00" to be interpreted as 1900
versus 2000. This could result in the possible failure of those programs and
devices to properly recognize date sensitive information when the year changes
to 2000. Systems that do not properly recognize date sensitive information could
generate erroneous data or a system failure. The Company's objective is to
ensure an uninterrupted transition into Year 2000 and has a plan currently in
place. The scope of the Year 2000 plan includes: (1) information technology
("IT") such as software and hardware; (2) non-IT systems or embedded technology
such as microcontrollers contained in various manufacturing and lab equipment,
environmental and safety systems, facilities and utilities and Company



                                       10
<PAGE>   11

products with date sensitivity; and (3) readiness of key third parties,
including suppliers, customers and key financial institutions.

The Company has a formal Year 2000 compliance project that addresses the
Company's information technology systems. The Company has identified the
following phases of its Year 2000 project: 1) educate IT personnel and company
management about Year 2000 issue, 2) identify required resources to execute the
Year 2000 action plan, 3) create priority schedule for critical systems, 4)
estimate total cost of Year 2000 action plan, 5) determine and implement
corrections to non-compliant systems, 6) test and verify corrections, 7) place
corrected systems into service, and 8) monitor Year 2000 compliance with new
vendors, software and hardware. Phases 1 through 5 have been completed. Phases 6
and 7 are on schedule to be completed by the end of 1999. Phase 8 will continue
into the year 2000.

The Company has requested written confirmation from what it believes to be all
of its significant vendors as to their Year 2000 compliance status, and has
taken steps to determine the extent to which the Company's systems are
vulnerable to those third parties' failures to remedy their own Year 2000
issues. There can be no assurance that the systems of other companies with which
the Company does business will be timely converted or that any such failure to
upgrade or convert would not have an adverse effect on the Company's systems and
operations. However responses to date have indicated no significant problems.

Through the second quarter 1999, the Company has incurred less than $25,000 of
Year 2000 costs and expects to spend less than $10,000 during each of 1999 and
2000. All costs associated with Year 2000 compliance are being funded with cash
flow generated from operations and existing cash balances and are being expensed
as incurred.

The Company believes that the most reasonably likely worst-case scenario arising
from the Year 2000 issue is a temporary interruption in the Company's operations
resulting from non-compliant systems of third parties. Based on the status of
its Year 2000 compliance program, the Company currently believes that the Year
2000 issue will not pose significant operational problems for the Company's
internal computer systems. However, the company does not have, nor plan to have,
a formal contingency plan in the event its Year 2000 compliance program is
unsuccessful or not completed on a timely basis.


ITEM 3.  QUANTITATIVE AND QUALITATIVE DISCLOSURE OF MARKET RISK

The Company does not use derivative financial instruments in its operations or
investment portfolio. The Company does not have material exposure to market risk
associated with changes in interest rates as it has no long-term debt
obligations outstanding. The Company does not believe it has any other material
exposure to market risk associated with interest rates.

The Company sells to customers in foreign markets through our foreign
operations. These transactions are often denominated in currencies other than
the U.S. dollar. Our primary currency exposures are the British Pound and the
Euro. Foreign currency transaction gains and losses were not material to the
Company's results of operations for the quarter ended July 3, 1999. However, the
Company has experienced a material fluctuation in intercompany foreign currency
translation as of the end of the second quarter of 1999 due to a decline in the
British Pound exchange rate. To date, the Company has not entered into any
significant foreign currency forward exchange contracts or other derivative
financial instruments to hedge the effects of adverse fluctuations in foreign
currency exchange.



                                       11
<PAGE>   12

Forward-Looking Statements

The portions of this report that relate to future plans, events or performance
are forward-looking statements. Investors are cautioned that all such statements
involve risks and uncertainties, including announcements by the Company's
competitors, risks related to the government regulatory approval processes,
delays in product development and new product introductions, rapidly changing
technology, an intensely competitive market, market acceptance of new products,
relationships with foreign distributors, reimbursement policies and general
economic conditions. These factors, and others, are discussed more fully in the
Company's annual report on Form 10-K for the fiscal year ended January 2, 1999,
and the Company's other filings with the Securities and Exchange Commission.
Actual results, events or performance may differ materially. These
forward-looking statements speak only as of the date hereof. The Company
undertakes no obligation to publicly release the result of any revisions to
these forward-looking statements that may be made to reflect events or
circumstances after the date hereof or to reflect the occurrence of
unanticipated events.



                                       12
<PAGE>   13

                           PART II. OTHER INFORMATION

ITEM 4.  SUBMISSION OF MATTERS TO A VOTE OF SECURITY-HOLDERS

The annual meeting of Shareholders was held on May 14, 1999. The following items
were voted upon and approved at the meeting:

1.  To elect directors to serve for the ensuing year and until their successors
    are elected.

<TABLE>
<CAPTION>
                           Number of Votes

                                For             Withheld
                                ---             --------
<S>                          <C>                <C>
Christy W. Bell .......      17,625,075         265,897
Howard E. Chase .......      17,626,991         263,981
J. Daniel Cole ........      17,626,991         263,981
D. Keith Grossman .....      17,626,909         264,063
J. Donald Hill ........      17,626,991         263,981
William M. Hitchcock ..      17,626,991         263,981
George W. Holbrook, Jr.      17,628,924         262,048
Daniel M. Mulvena .....      17,628,924         262,048
</TABLE>

2.  Amendment to the 1997 Stock Option Plan with respect to the proposal to
    approve the amendment to Thoratec's 1997 Stock Option Plan, including an
    increase in the number of shares reserved for issuance under the plan from
    1,000,000 to 2,800,000:

<TABLE>
<CAPTION>
                        For           Against        Abstain      Not Voted
                        ---           -------        -------      ---------
                    <S>              <C>             <C>          <C>
                    11,325,975       2,610,820       25,301       3,928,876
</TABLE>

3.  Amendments to the 1996 Nonemployee Directors Stock Option Plan with respect
    to the proposal to approve the amendments to Thoratec's 1996 Nonemployee
    Directors Stock Option Plan, including an increase in the number of shares
    reserved for issuance under the plan from 150,000 to 350,000:

<TABLE>
<CAPTION>
                      For           Against        Abstain      Not Voted
                      ---           -------        -------      ---------
                  <S>              <C>             <C>          <C>
                  12,240,220       1,694,643       27,233       3,928,876
</TABLE>



                                       13
<PAGE>   14

ITEM 6.  EXHIBITS AND REPORTS ON FORM 8-K

    (a)  Exhibits required by Item 601 of Regulation S-K

         See Exhibit Index on the page immediately preceding exhibits.

    (b)  Reports on Form 8-K

         No reports on Form 8-K were filed during the quarter.



                                       14
<PAGE>   15

                                   SIGNATURES



In accordance with the requirements of the Exchange Act, the registrant caused
this report to be signed on its behalf by the undersigned, thereunto duly
authorized.




                                        THORATEC LABORATORIES CORPORATION

<TABLE>
<S>                                     <C>
Date: July 20, 1999                               /s/ D. Keith Grossman
                                        -----------------------------------------------
                                          D. Keith Grossman, Chief Executive Officer


Date: July 20, 1999                               /s/ Cheryl D. Hess
                                        -----------------------------------------------
                                            Cheryl D. Hess, Chief Financial Officer
</TABLE>



                                       15
<PAGE>   16

                                  EXHIBIT INDEX


<TABLE>
<CAPTION>
   Exhibit Number                                Document
   --------------                                --------
   <S>                                  <C>
        27                              Financial Data Schedule
</TABLE>



                                       16