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                                                                     EXHIBIT 4.4

                                                                  EXECUTION COPY

                          REGISTRATION RIGHTS AGREEMENT

                               DATED MAY 24, 2004

                                     BETWEEN

                              THORATEC CORPORATION

                                       AND

                               MERRILL LYNCH & CO.

                      MERRILL LYNCH, PIERCE, FENNER & SMITH
                                  INCORPORATED
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                          REGISTRATION RIGHTS AGREEMENT

      This Registration Rights Agreement (the "AGREEMENT") is made and entered
into this 24th day of May 2004, between Thoratec Corporation, a California
corporation (the "COMPANY"), and Merrill Lynch, Pierce, Fenner & Smith
Incorporated (the "INITIAL PURCHASER"). This Agreement is made pursuant to the
Purchase Agreement, dated May 18, 2004, between the Company and the Initial
Purchaser (the "PURCHASE AGREEMENT"), which provides for the sale by the Company
to the Initial Purchaser of $247,427,000 aggregate principal amount at maturity
of the Company's Senior Subordinated Convertible Notes due 2034 (the "NOTES"),
(which includes $32,273,000 aggregate principal amount at maturity of Notes
pursuant to the Initial Purchaser's option to purchase as set forth in Section
2(b) of the Purchase Agreement). In order to induce the Initial Purchaser to
enter into the Purchase Agreement and in satisfaction of a condition to the
Initial Purchaser's obligations thereunder, the Company has agreed to provide
the registration rights provided for in this Agreement, pursuant to Section 5(g)
of the Purchase Agreement. In consideration of the foregoing, the parties hereto
agree, for the benefit of the beneficial owners (including the Initial
Purchaser) from time to time of the Registrable Securities (as defined herein)
(each of the foregoing, a "HOLDER" and collectively, the "HOLDERS"), as follows:

      1. Definitions.

      Capitalized terms used and not defined in this Agreement shall have the
meaning given to them in the Indenture. As used in this Agreement, the following
capitalized defined terms shall have the following meanings:

      "1933 ACT" shall mean the Securities Act of 1933, as amended from time to
time, and the rules and regulations of the SEC promulgated thereunder.

      "1934 ACT" shall mean the Securities Exchange Act of 1934, as amended from
time to time, and the rules and regulations of the SEC promulgated thereunder.

      "CLOSING DATE" shall mean the Closing Time as defined in the Purchase
Agreement.

      "COMMON STOCK" shall mean any shares of the common stock of the Company,
no par value, and any other shares of common stock as may constitute "Common
Stock" for purposes of the Indenture, including the Underlying Common Stock (as
defined in the Indenture).

      "COMPANY" shall have the meaning set forth in the preamble to this
Agreement and also includes the Company's successors.

      "DEPOSITARY" shall mean The Depository Trust Company, or any other
depositary appointed by the Company; provided, however, that any such depositary
must have an address in The Borough of Manhattan, The City of New York.

      "EFFECTIVENESS PERIOD" shall have the meaning set forth in Section 2.1(a)
hereof.

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      "EFFECTIVENESS TARGET DATE" shall mean the one hundred eightieth (180th)
day after the Closing Date.

      "EVENT DATE" shall have the meaning set forth in Section 2.4 hereof.

      "FILING DATE" shall mean the ninetieth (90th) day after the Closing Date.

      "FILING DEFAULT" shall have the meaning set forth in Section 2.4 hereof.

      "HOLDER" or "HOLDERS" shall have the meaning specified in the preamble to
this Agreement.

      "INDENTURE" shall mean the Indenture relating to the Notes, dated as of
May 24, 2004, between the Company and U.S. Bank National Association, as
trustee, as the same may be amended, supplemented, waived or otherwise modified
from time to time in accordance with the terms thereof.

      "INITIAL PURCHASER" shall have the meaning set forth in the preamble to
this Agreement.

      "LIQUIDATED DAMAGES" shall have the meaning set forth in Section 2.4
hereof.

      "MAJORITY HOLDERS" shall mean the Holders of a majority of the aggregate
principal amount at maturity of Registrable Securities outstanding; provided,
however, that whenever the consent or approval of Holders of a specified
percentage of Registrable Securities is required hereunder, Registrable
Securities held by the Company or any of its affiliates (as such term is defined
in Rule 405 under the 1933 Act) shall be disregarded in determining such
specified percentage.

      "NASD" shall mean the National Association of Securities Dealers, Inc.

      "NOTES" shall have the meaning set forth in the preamble to this
Agreement.

      "OFFERING MEMORANDUM" means the final Offering Memorandum of the Company,
dated May 18, 2004, relating to the sale of the Notes.

      "PERSON" shall mean an individual, partnership, corporation, limited
liability company, joint venture, trust or unincorporated organization, or a
government or agency or political subdivision thereof.

      "PROSPECTUS" shall mean the prospectus included in any Registration
Statement, including a prospectus that discloses information previously omitted
from a prospectus filed as part of an effective registration statement in
reliance upon Rule 415 of the 1933 Act, and any such prospectus as amended or
supplemented by any prospectus supplement, with respect to the terms of the
offering of any portion of the Registrable Securities covered by such
Registration Statement, and all other amendments and supplements to any such
prospectus, including post-effective amendments, and in each case including all
material incorporated or deemed to be incorporated by reference therein.

      "PURCHASE AGREEMENT" shall have the meaning set forth in the preamble to
this Agreement.

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      "QUESTIONNAIRE" shall have the meaning set forth in Section 2.1(d) hereof.

      "REGISTRABLE SECURITIES" shall mean the Notes and the shares of Common
Stock into which the Notes are convertible, upon original issuance thereof, and
at all times subsequent thereto; provided, however, that any Securities shall
cease to be Registrable Securities when (i) a Registration Statement with
respect to such Securities shall have been declared effective under the 1933 Act
and such Securities shall have been disposed of pursuant to such Registration
Statement, (ii) such Securities shall have been sold to the public pursuant to
Rule 144 (or any similar provision then in force, but not Rule 144A) under the
1933 Act, (iii) such Securities may be sold or transferred by a person who is
not an affiliate (as such term is defined in Rule 144(a)(1) under the 1933 Act)
of the Company pursuant to Rule 144 without any volume restrictions thereunder
or (iv) such Securities shall have ceased to be outstanding.

      "REGISTRATION DEFAULT" shall have the meaning set forth in Section 2.4
hereof.

      "REGISTRATION EXPENSES" shall mean any and all expenses incident to
performance of or compliance by the Company with this Agreement, including
without limitation: (i) all SEC, stock exchange or NASD registration and filing
fees, including, if applicable, the fees and expenses of any "qualified
independent underwriters" (and its counsel) that is required to be retained by
any holder of Registrable Securities in accordance with the rules and
regulations of the NASD, (ii) all fees and expenses incurred in connection with
compliance with state or other securities or blue sky laws and compliance with
the rules of the NASD (including reasonable fees and disbursements of counsel
for any Underwriters or Holders in connection with qualification of any
Registrable Securities under state or other securities or blue sky laws and any
filing with and review by the NASD), (iii) all expenses of any Persons in
preparing or assisting in preparing, word processing, printing and distributing
any Registration Statement, any Prospectus, any amendments or supplements
thereto, any underwriting agreements, securities sales agreements, certificates
representing the Securities and other documents relating to the performance of
and compliance with this Agreement, (iv) all fees and expenses incurred in
connection with the listing, if any, of any of the Registrable Securities on any
securities exchange or exchanges or on any quotation system, (v) all rating
agency fees, (vi) all fees and disbursements relating to the qualification of
the Indenture under applicable securities laws, (vii) the fees and disbursements
of counsel for the Company and the fees and expenses of independent public
accountants for the Company or for any other Person, business or assets whose
financial statements are included in any Registration Statement or Prospectus,
including, in the event of an underwritten offering of Registrable Securities,
the expenses for up to a total of 3 requests for special audits or "comfort
letters" required by or incident to such performance and compliance, (viii) the
fees and expenses of the Trustee, any registrar, any depositary, any paying
agent, any escrow agent, any transfer agent or any custodian, in each case
including their respective counsel, (ix) the reasonable fees and expenses of the
Holders in connection with the Shelf Registration, including the reasonable fees
and expenses of one counsel to the Holders of Registrable Securities, designated
by the Company and reasonably acceptable to the Initial Purchaser and (x) any
fees and disbursements of the Underwriters customarily paid by issuers or
sellers of securities and the fees and expenses of any special experts retained
by the Company in connection with any Registration Statement, but

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excluding underwriting discounts and commissions and any transfer taxes, if any,
relating to the sale or disposition of Registrable Securities by a Holder.

      "REGISTRATION STATEMENT" shall mean any registration statement of the
Company pursuant to the provisions of Section 2 of this Agreement that covers
any of the Registrable Securities held by Holders that have provided all the
information required pursuant to the terms of Section 2.1(d) hereof and that is
on an appropriate form under Rule 415 under the 1933 Act, or any similar rule
that may be adopted by the SEC, and all amendments and supplements to such
registration statement, including post-effective amendments, in each case
including the Prospectus contained therein, all exhibits thereto and all
material incorporated or deemed to be incorporated by reference therein,
including each Subsequent Registration Statement from the time such Subsequent
Registration Statement is filed pursuant to Section 2.1(a) hereof.

      "RULE 144" shall mean Rule 144 under the 1933 Act, as such Rule may be
amended from time to time, or any similar or successor rule or regulation
hereafter adopted by the SEC having substantially the same effect as such Rule.

      "SEC" shall mean the United States Securities and Exchange Commission or
any successor agency or government body performing the functions currently
performed by the United States Securities and Exchange Commission.

      "SECURITIES" shall mean the Notes and the shares of Common Stock into
which the Notes are convertible, upon original issuance thereof, and at all
times subsequent thereto.

      "SUBSEQUENT REGISTRATION STATEMENT" shall have the meaning set forth in
Section 2.1(a) hereof.

      "SHELF REGISTRATION" shall have the meaning set forth in Section 2.1(a)
hereof.

      "TIA" shall mean the Trust Indenture Act of 1939, as amended from time to
time, and the rules and regulations of the SEC promulgated thereunder.

      "TRUSTEE" shall mean the trustee with respect to the Notes under the
Indenture.

      "UNDERWRITERS" shall have the meaning set forth in Section 4(a) hereof.

      For purposes of this Agreement, (i) all references in this Agreement to
any Registration Statement or Prospectus or any amendment or supplement to any
of the foregoing shall be deemed to include the copy filed with the SEC pursuant
to its Electronic Data Gathering, Analysis and Retrieval system; (ii) all
references in this Agreement to financial statements and schedules and other
information that is "contained", "included" or "stated" in any Registration
Statement or Prospectus (or other references of like import) shall be deemed to
mean and include all such financial statements and schedules and other
information that is incorporated or deemed to be incorporated by reference in
such Registration Statement or Prospectus, as the case may be; and (iii) all
references in this Agreement to amendments or supplements to any Registration
Statement or

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Prospectus shall be deemed to mean and include the filing of any document under
the 1934 Act that is incorporated or deemed to be incorporated by reference in
such Registration Statement or Prospectus, as the case may be.

      2.    Registration Under the 1933 Act.

            2.1   Shelf Registration.

                  (a) As promptly as reasonably practicable, but no later than
the Filing Date, the Company shall file with the SEC, a Registration Statement
for an offering to be made on a continuous basis pursuant to Rule 415 under the
1933 Act registering the resales of all of the Registrable Securities held by
Holders that have provided the information pursuant to Section 2.1(d) hereof
(the "SHELF REGISTRATION"). The Shelf Registration shall be on Form S-3 under
the 1933 Act or another appropriate form permitting registration of such
Registrable Securities for resale by the Holders in the manner or manners
reasonably designated by them (including, without limitation, one or more
underwritten offerings). The Company shall use its reasonable best efforts to
cause the Registration Statement to be declared effective by the SEC as promptly
as reasonably practicable, but no later than the Effectiveness Target Date; and
(subject to Section 2.3(b) below) to keep the Registration Statement
continuously effective, supplemented and amended, as required in order to permit
the Prospectus forming a part thereof to be useable by the Holders until the
earliest to occur of (i) the expiration of the holding period applicable to the
Registrable Securities held by persons that are not affiliates (as such term is
defined in Rule 405 under the 1933 Act) of the Company under Rule 144(k) under
the 1933 Act or any successor provision (assuming that such Registrable
Securities have been held since the date of original issuance, by Holders that
are not affiliates of the Company), (ii) the date when the Holders are able to
sell all of their Registrable Securities immediately without restriction
pursuant to the volume limitation provisions of Rule 144 or otherwise, and (iii)
all of the Registrable Securities covered by the Registration Statement have
been sold pursuant to the Registration Statement (the "EFFECTIVENESS PERIOD").
If the Registration Statement ceases to be effective at any time during the
Effectiveness Period, the Company shall use its reasonable best efforts to
obtain prompt withdrawal of any order suspending the effectiveness thereof, and
in any event shall within thirty (30) days after such cessation of effectiveness
amend the Registration Statement in a manner reasonably expected by the Company
to obtain the withdrawal of the order suspending the effectiveness thereof, or
file an additional Registration statement covering all of the securities that of
the date of such filing are Registrable Securities held by Holders that have
provided the information pursuant to Section 2.1(d) hereof (a "SUBSEQUENT
REGISTRATION STATEMENT"). If a Subsequent Registration Statement is filed, the
Company shall use its reasonable best efforts to cause the Subsequent
Registration Statement to become effective as promptly as is reasonably
practicable after such filing or, if filed during a period in which use of the
Prospectus is suspended, after expiration of such suspension period (without
prejudice to the Company's obligation to pay Liquidated Damages under Section
2.4 hereof), and to keep such Registration Statement (or Subsequent Registration
Statement), subject to the Company's right to suspend the Registration Statement
as described in Section 3(h) hereof, continuously effective until the end of the
Effectiveness Period.

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                  (b) Notwithstanding any other provisions hereof, the Company
shall use its reasonable best efforts to ensure that (i) any Registration
Statement and any amendment thereto and any Prospectus forming a part thereof
and any supplements thereto complies in all material respects with the 1933 Act,
(ii) any Registration Statement and any amendment thereto does not, when it
becomes effective, contain an untrue statement of a material fact or omit to
state a material fact required to be stated therein or necessary to make the
statements therein not misleading and (iii) any Prospectus forming a part of any
Registration Statement and any amendment or supplement to such Prospectus does
not include an untrue statement of a material fact or omit to state a material
fact necessary in order to make the statements therein, in the light of the
circumstances under which they were made, not misleading.

                  (c) The Company shall not permit any securities other than
Registrable Securities to be included in the Registration Statement. The Company
further agrees, if necessary, to supplement or amend the Registration Statement,
as required by Section 3(b) below.

                  (d) Notwithstanding any other provision hereof, no Holder of
Registrable Securities may include any of its Registrable Securities in the
Registration Statement pursuant to this Agreement unless the Holder furnishes to
the Company a fully completed questionnaire in the form attached as Annex A to
the Offering Memorandum (the "QUESTIONNAIRE") and such other information in
writing as the Company may reasonably request in writing for use in connection
with the Registration Statement or Prospectus included therein and in any
application to be filed with or under state securities laws. In order to be
named as a selling securityholder in the Prospectus at the time of effectiveness
of the Registration Statement, each Holder must, before the effectiveness of the
Registration Statement and no later than the 20th day after receipt of the
notice by such Holder from the Company of the initial filing of the Registration
Statement (or the filing of the first amendment to the Registration Statement in
the event the Company promptly files the Registration Statement following the
date of this Agreement) (which notice shall include the Questionnaire), furnish
the completed Questionnaire and such other information, if any, to the Company
in writing and the Company will include the information from the completed
Questionnaire and such other information, if any, in the Registration Statement
and the Prospectus in a manner so that upon effectiveness of the Registration
Statement the Holder will be permitted to deliver the Prospectus to purchasers
of the Holder's Securities. From and after the date that the Registration
Statement is first declared effective by the SEC, upon receipt of a completed
Questionnaire and such other information, if any, the Company will use its
reasonable best efforts to file within 15 business days after receipt any
amendments or supplements to the Registration Statement necessary for a Holder
to be named as a selling securityholder in the Prospectus contained therein to
permit such Holder to deliver the Prospectus to purchasers of the Holder's
Securities (subject to the Company's right to suspend the Registration Statement
as described in Section 2.3(b) below). Holders that do not deliver a completed
written Questionnaire and such other information, as provided for in this
Section 2.1(d), will not be named as selling securityholders in the Prospectus.
Each Holder named as a selling securityholder in the Prospectus agrees, as a
condition to such Holder's use of the Registration Statement and the Prospectus,
to furnish in a timely manner to the Company all information required to be
disclosed in order to make information previously furnished to the Company by
the Holder not materially misleading and any other information regarding such
Holder

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and the distribution of such Holder's Registrable Securities as the Company may
from time to time reasonably request in writing.

            2.2   Expenses. The Company shall pay all Registration Expenses in
connection with the Shelf Registration and any Registration Statement. Each
Holder shall pay all fees and disbursements of its counsel (other than as set
forth in the definition of Registration Expenses) and all underwriting discounts
and commissions and transfer taxes, if any, relating to the sale or disposition
of such Holder's Registrable Securities pursuant to the Registration Statement.

            2.3   Effectiveness.

                  (a)   The Registration Statement shall not be deemed to have
become effective unless it has been declared effective by the SEC; provided,
however, that if, after it has been declared effective, the offering of
Registrable Securities pursuant to the Registration Statement is interfered with
by any stop order, injunction or other order or requirement of the SEC or any
other governmental agency or court, such Registration Statement shall be deemed
not to have been effective during the period of such interference, until the
offering of Registrable Securities pursuant to such Registration Statement may
legally resume.

                  (b)   The Company may suspend the use of the Registration
Statement and any Prospectus related to the Registration Statement for a period
not to exceed 45 days in any consecutive three-month period and not to exceed an
aggregate of 120 days in any consecutive twelve-month period if the Board of
Directors of the Company shall have determined in good faith that because of
valid business reasons including, without limitation, the acquisition or
divestiture of assets, pending corporate developments, public filings with the
Commission and similar event (but not including avoidance of the Company's
obligations hereunder), it is in the interest of the Company to suspend such use
and, prior to suspending such use the Company provides the Holders with written
notice of such suspension, which notice need not specify the nature of the event
giving rise to such suspension.

            2.4   Liquidated Damages. No Holder of Registrable Securities shall
be entitled to Liquidated Damages pursuant to this Section 2.4 unless such
Holder timely furnished to the Company a completed Questionnaire. The Company
and the Initial Purchaser agree that the Holders of Registrable Securities will
suffer damages if the Company fails to fulfill its obligations under Section 2.1
hereof and further agree that the Liquidated Damages provided for in this
Section 2.4 constitute a reasonable estimate of the damages that may be incurred
by Holders of Registrable Securities by reason of a Registration Default.
Therefore, the Company and the Initial Purchaser agree that the sole remedy for
a violation of the terms of this Agreement with respect to which Liquidated
Damages are expressly provided for (including any non-compliance with a covenant
that results, directly or indirectly, in a Registration Default) shall be such
Liquidated Damages. Accordingly, the Company agrees to pay liquidated damages on
the Registrable Securities to the Holders that furnish to the Company a
completed Questionnaire in accordance with Section 2.1(d) ("LIQUIDATED DAMAGES")
under the circumstances and to the extent as set forth below. In the event that
(a) the Registration Statement has not been filed with the SEC on or prior to
the Filing Date, (b) the Registration Statement is not declared effective by the
SEC on or prior to the Effectiveness

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Target Date, (c) the Registration Statement has been declared effective by the
SEC and such Registration Statement ceases to be effective or usable at any time
during the Effectiveness Period for any reason (other than as specified in
Section 2.3(b)) without being succeeded within seven business days by a
post-effective amendment to such Registration Statement, a supplement to the
Prospectus or a report filed with the SEC pursuant to the 1934 Act that cures
such failure or (d) the Company suspends the use of the Registration Statement
and any Prospectus related to the Registration Statement for a period exceeding
forty-five (45) days in any consecutive three-month period or exceeding an
aggregate of one hundred twenty (120) days in any consecutive twelve-month
period (each such event referred to in clauses (a) through (d) above, a
"REGISTRATION DEFAULT"), then the interest rate borne by the Notes shall be
increased as Liquidated Damages (x) by one-quarter of one percent (0.25%) per
annum from the day following the day of the occurrence of such Registration
Default up to and including the ninetieth (90th) day following such Registration
Default and (y) by one half of one percent (0.50%) from and after the
ninety-first (91st) day following the occurrence of such Registration Default,
provided that the aggregate increase in such interest rate will in no event
exceed one half of one percent (0.50%) per annum. Immediately and automatically,
upon the cure of such Registration Default, the accrual of Liquidated Damages
will cease and the interest rate will revert to the original rate so long as no
other Registration Default shall have occurred and shall be continuing at such
time; provided, however, that, if after any such reduction in interest rate, one
or more Registration Defaults shall again occur, the interest rate shall again
be increased pursuant to the foregoing provisions. A Registration Default under
clause (a) above shall be cured on the date that the Registration Statement is
filed with the SEC; a Registration Default under clause (b) above shall be cured
on the date that the Registration Statement is declared effective by the SEC; a
Registration Default under clause (c) above shall be cured on the date an
amended Registration Statement is declared effective or the Company otherwise
declares the Registration Statement and the Prospectus useable; and a
Registration Default under clause (d) above shall be cured on the date the
Prospectus is declared useable by the Company. In the event of a Registration
Default, the Company shall pay Liquidated Damages (x) to Holders of Notes that
are Registrable Securities based on the principal amount at maturity of Notes
held by such Holders and (y) to Holders who have converted any of their Notes
into Common Stock, only in respect of the Notes then held by the Holder in
accordance with (x). A Holder that has converted all of such Holder's Notes into
Common Stock shall not be entitled to receive any Liquidated Damages.

                  The Company shall notify the Trustee in writing within three
business days after each and every date on which a Registration Default occurs
(an "EVENT DATE"). Liquidated Damages shall be paid by the Company to the
Holders of Notes by depositing with the Trustee, in trust, for the benefit of
the Holders of Notes, on or before the Interest Payment Date next following the
date of such Registration Default, immediately available funds in sums
sufficient to pay the Liquidated Damages then due. Such Liquidated Damages due
shall be payable on each such Interest Payment Date to the record Holder of
Notes entitled to receive the interest payment to be paid on such Interest
Payment Date as set forth in the Indenture. Liquidated Damages in respect of
Notes that are converted into Common Stock in the period between the Event Date
and the Payment Date shall be payable by the Company to the Holders of Common
Stock issued upon conversion of such Notes concurrently with the payment of
Liquidated Damages to the Holders of Notes. Liquidated Damages shall accrue from
and including the day following the applicable Event Date to but

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excluding the earliest to occur of (1) the date the relevant Registration
Default is cured, (2) the expiration of the Effectiveness Period and (3) the
date on which the relevant Notes either (i) cease to be Registrable Securities
or (ii) are converted into Common Stock.

            In addition, from and after the date that the Registration Statement
is first declared effective, if the Company fails to file any amendment or
supplement to the Registration Statement or Prospectus to name any Holder as a
selling securityholder in the Prospectus in the manner and within the time
periods specified in Section 2.1(d) (in each case, a "FILING DEFAULT"), the
Company shall pay Liquidated Damages with respect to such Filing Default to such
Holder in the manner and in such amounts as contemplated in the first and second
paragraphs of this Section 2.4, unless the Company is already required under
this Section 2.4 to pay Liquidated Damages with respect to a Registration
Default occurring during the same period. Any Liquidated Damages payable with
respect to a Filing Default shall accrue from and including the day after the
last day of the applicable time period specified in Section 2.1(d) to but
excluding the earliest to occur of (1) the date such Filing Default is cured,
(2) the expiration of the Effectiveness Period or (3) the date on which the
relevant Notes either (i) cease to be Registrable Securities or (ii) are
converted into Common Stock.

      3.    Registration Procedures.

            In connection with the obligations of the Company with respect to
the Shelf Registration and the Registration Statement pursuant to Section 2
hereof, the Company shall:

                  (a) prepare and file with the SEC a Registration Statement
within the period specified in Section 2, on the appropriate form under the 1933
Act, which form (i) shall be selected by the Company and (ii) shall be available
for the sale of the Registrable Securities by the selling Holders thereof, and
such Registration Statement shall comply as to form in all material respects
with the applicable requirements of the 1933 Act and shall include or
incorporate by reference all financial statements required by the SEC to be
filed therewith or incorporated by reference therein, and use its reasonable
best efforts to cause such Registration Statement to become effective and remain
effective in accordance with Section 2 hereof;

                  (b) prepare and file with the SEC such amendments and
post-effective amendments to the Registration Statement as may be necessary
under applicable law to keep such Registration Statement effective for the
Effectiveness Period (subject to Section 2.3(b) hereof); cause each Prospectus
to be supplemented as required and, as so supplemented, to be filed pursuant to
Rule 424 (or any similar provision then in force) under the 1933 Act; and comply
during the Effectiveness Period with the provisions of the 1933 Act and the 1934
Act required to enable the disposition by selling Holders of all Registrable
Securities covered by the Registration Statement in accordance with the intended
method or methods of distribution by such selling Holders;

                  (c) (i) notify each Holder of Registrable Securities, as
promptly as practicable, but in any event no less than seven days after filing,
that a Registration Statement with respect to the Registrable Securities has
been filed (which notice shall be in the form of Annex A to the Offering
Memorandum and include the Questionnaire); (ii) upon prior request, furnish to
each Holder of Registrable Securities, to counsel for the Holders, and to each
Underwriter of an underwritten

                                      -9-
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offering of Registrable Securities, if any, without charge, as many copies of
the Prospectus included therein, including each preliminary Prospectus (in the
event of an underwritten offering), and any amendment or supplement thereto as
such Holder, counsel or Underwriter shall reasonably request in order to
facilitate the public sale or other disposition of the Registrable Securities;
and (iii) subject to Section 2.3(b) hereof and to any notice by the Company in
accordance with Section 3(h) hereof of the existence of any fact of the kind
described in Sections 3(e)(iii), 3(e)(v) and 3(e)(vi) hereof, the Company hereby
consents to the use of the Prospectus, including each preliminary Prospectus (in
the event of an underwritten offering), that is contained in a Registration
Statement declared effective by the SEC, or any amendment or supplement thereto
by each of the Holders and Underwriters of Registrable Securities in connection
with the offering and sale of the Registrable Securities covered by any
Prospectus that is contained in a Registration Statement declared effective by
the SEC or any amendment or supplement thereto;

                  (d) use its reasonable best efforts to register or qualify (or
establish an exemption from such registration or qualification for) the
Registrable Securities for offer and sale under all applicable state securities
or "blue sky" laws of such jurisdictions as any Holder of Registrable Securities
covered by a Registration Statement and each Underwriter of an underwritten
offering of Registrable Securities shall reasonably request, to cooperate with
the Holders and the Underwriters of any Registrable Securities in connection
with any filings required to be made with the NASD, to keep each such
registration or qualification effective during the period necessary for such
offer and sale, and do any and all other acts and things which may be reasonably
necessary or advisable to enable such Holder and Underwriter to consummate the
disposition in each such jurisdiction of such Registrable Securities owned by
such Holder; provided, however, that the Company shall not be required to (i)
qualify as a foreign corporation or as a dealer in securities in any
jurisdiction where it would not otherwise be required to qualify but for this
Section 3(d) or (ii) take any action which would subject it to general service
of process or taxation in any such jurisdiction if it is not then so subject;

                  (e) notify each Holder of Registrable Securities as promptly
as reasonably practicable and, if requested by such Holder, confirm such advice
in writing as promptly as reasonably practicable (i) when a Registration
Statement has become effective and when any post-effective amendments and
supplements thereto become effective, (ii) of any request by the SEC or any
state securities authority for post-effective amendments or supplements to a
Registration Statement or Prospectus or for additional information after a
Registration Statement has become effective, (iii) of the issuance by the SEC or
any state securities authority of any stop order suspending the effectiveness of
a Registration Statement or the initiation of any proceedings for that purpose,
(iv) if between the effective date of a Registration Statement and the closing
of any sale of Registrable Securities covered thereby, the representations and
warranties of the Company contained in any underwriting agreement, securities
sales agreement or other similar agreement, if any, relating to such offering
cease to be true and correct in all material respects, (v) of the happening of
any event or the discovery of any facts during the period a Registration
Statement is effective which cause (A) the Registration Statement and any
amendment thereto to contain an untrue statement of a material fact or omit to
state a material fact required to be stated therein or necessary to make the
statements therein not misleading or (B) any Prospectus forming a part of the
Registration Statement

                                      -10-
<PAGE>

and any amendment or supplement to such Prospectus to include an untrue
statement of a material fact or omit to state a material fact necessary in order
to make the statements therein, in the light of the circumstances under which
they were made, not misleading, (vi) of the receipt by the Company of any
notification with respect to the suspension of the qualification of the
Registrable Securities for sale in the United States or any state thereof or the
initiation or threatening of any proceeding for such purpose and (vii) of any
reasonable determination by the Company that a post-effective amendment to a
Registration Statement would be appropriate and (viii) of the commencement and
completion of any period of suspension under Section 2.3(b) hereof;

                  (f) use its reasonable best efforts to obtain the withdrawal
of any order suspending the effectiveness of a Registration Statement as soon as
practicable and provide notice as promptly as reasonably practicable to each
Holder of the withdrawal of any such order;

                  (g) cooperate with the selling Holders of Registrable
Securities to facilitate the timely preparation and delivery of certificates
representing Registrable Securities to be sold and not bearing any restrictive
legends; and cause such Registrable Securities to be in such denominations
(consistent with the provisions of the Indenture) and registered in such names
as the selling Holders or the Underwriters, if any, may reasonably request in
writing at least three business days prior to the closing of any sale of
Registrable Securities;

                  (h) upon the occurrence of any event or the discovery of any
facts described in Section 3(e)(ii), 3(e)(iii), 3(e)(iv), 3(e)(v) or 3(e)(vi)
hereof, as promptly as practicable after the occurrence of such an event, use
its reasonable best efforts to prepare a supplement or post-effective amendment
to a Registration Statement or the related Prospectus or any document
incorporated or deemed to be incorporated therein by reference or file any other
required document so that use of the Registration Statement or the Prospectus,
as the case may be, by selling Holders in the manner and for the purposes
contemplated by this Agreement may be resumed as promptly as practicable and the
Prospectus, as thereafter delivered to the purchasers of Registrable Securities,
will not contain at the time of such delivery any untrue statement of a material
fact or omit to state a material fact necessary in order to make the statements
therein, in the light of the circumstances under which they were made, not
misleading. The Company agrees to notify each Holder to suspend use of the
Prospectus as promptly as practicable after the occurrence of an event described
in Section 3(e)(ii), 3(e)(iii), 3(e)(iv), 3(e)(v) or 3(e)(vi) hereof, and each
Holder hereby agrees to suspend use of the Prospectus until notification is
given by the Company that such use of the Prospectus may be resumed. If use of
the Prospectus is suspended, the Company agrees promptly to notify each Holder
when a determination is made that use of the Prospectus in the manner and for
the purposes contemplated by this Agreement may be resumed and to furnish each
Holder such number of copies of the Prospectus, as then amended or supplemented,
as such Holder may reasonably request;

                  (i) a reasonable time prior to the filing of any Registration
Statement, any Prospectus, any amendment to a Registration Statement or
amendment or supplement to a Prospectus, provide copies of such document to the
Initial Purchaser on behalf of such Holders if requested by the Initial
Purchaser, provided that, notwithstanding clause (iii) of the last paragraph of
Section 1, the foregoing shall not require the delivery of documents to be filed
under the 1934 Act

                                      -11-
<PAGE>

that will be incorporated or deemed incorporated by reference in the
Registration Statement or the Prospectus;

                  (j) obtain CUSIP numbers for all Registrable Securities not
later than the effective date of a Registration Statement, and provide the
Trustee with printed certificates for the Registrable Securities in a form
eligible for deposit with the Depositary;

                  (k) cause the Indenture to be qualified under the TIA in
connection with the registration of the Registrable Securities, (ii) cooperate
with the Trustee and the Holders to effect such changes, if any, to the
Indenture as may be required for the Indenture to be so qualified in accordance
with the terms of the TIA and (iii) execute, and use its reasonable best efforts
to cause the Trustee to execute, all documents as may be required to effect such
changes, if any, and all other forms and documents required to be filed with the
SEC to enable the Indenture to be so qualified in a timely manner;

                  (l) enter into such customary agreements (including
underwriting agreements) and take all other customary, reasonable and
appropriate actions (including securing or providing other agreements or
certificates as reasonably requested). The above shall be done at (i) the
effectiveness of such Registration Statement (and, if appropriate, each
post-effective amendment thereto) and (ii) each closing under any underwriting
or similar agreement as and to the extent required thereunder;

                  (m) if reasonably requested in writing in connection with a
disposition of Registrable Securities pursuant to a Registration Statement, make
reasonably available for inspection during normal business hours by a
representative of the Holders of the Registrable Securities and any Underwriters
participating in any disposition pursuant to a Registration Statement and any
counsel or accountant retained by such Holders or Underwriters, all relevant
financial and other records, documents and properties of the Company reasonably
requested by any such Persons, and cause the appropriate officers, directors,
employees, and any other agents of the Company to make all information
reasonably requested by any such representative, Underwriter, special counsel or
accountant in connection with a Registration Statement reasonably available for
inspection during normal business hours, and make such representatives of the
Company reasonably available for discussion during normal business hours of such
documents as shall be reasonably requested by the Initial Purchaser; provided,
however, that such persons shall first agree in writing with the Company that
any information that is designated by the Company in writing as confidential at
the time of delivery of such information shall be kept confidential by such
persons and shall be used solely for the purposes of exercising rights under
this Agreement, unless (i) disclosure of such information is required by court
or administrative order or is necessary to respond to inquiries of regulatory
authorities, provided that such persons shall as promptly as reasonably
practicable provide written notice to the Company of any request by any such
regulatory authority for any such confidential information of the Company in
order to allow the Company a reasonable amount of time to seek an appropriate
protective order to prevent the disclosure of such information, (ii) disclosure
of such information is required by law (including any disclosure requirements
pursuant to federal securities laws in connection with the filing of any
Registration Statement or the use of any Prospectus referred

                                      -12-
<PAGE>

to in this Agreement); provided, however, that such persons shall as promptly as
reasonably practicable, provide written notice to the Company of any such
disclosure requirements, (iii) such information becomes generally available to
the public other than as a result of a disclosure or failure to safeguard by any
such person or (iv) such information becomes available to any such person from a
source other than the Company and such source is not bound by a confidentiality
agreement or otherwise obligated to keep such information confidential.

                  (n) a reasonable time prior to filing any Registration
Statement, any Prospectus forming a part thereof, any amendment to such
Registration Statement or amendment or supplement to such Prospectus (other than
supplements that do nothing more than name one or more Holders and provide
information with respect thereto), provide copies of such document upon request
to the Initial Purchaser or to the Underwriter or Underwriters of an
underwritten offering of Registrable Securities, if any, and, to counsel for the
Initial Purchaser or Underwriters, as the case may be, and make such changes in
any such document prior to the filing thereof as the Initial Purchaser or the
Underwriter or Underwriters, or any of their respective counsel may reasonably
request in writing within five business days after the delivery of such copies
by the Company; cause the representatives of the Company to be available for
discussion of such documents during normal business hours as shall be reasonably
requested by the Initial Purchaser on behalf of the Holders or any Underwriter
or any of their respective counsel; and shall not at any time make any filing of
any such document of which the Initial Purchaser on behalf of the Holders, their
counsel or any Underwriter or their counsel shall not have previously been
advised and furnished a copy or to which the Majority Holders, the Initial
Purchaser on behalf of the Holders, their counsel or any Underwriter or their
counsel shall reasonably object within a reasonable time period;

                  (o) use its reasonable best efforts to cause all Registrable
Securities to be listed on any securities exchange or inter-dealer quotation
system such as NASDAQ on which similar debt or equity securities issued by the
Company are then listed, if any;

                  (p) otherwise comply with all applicable rules and regulations
of the SEC and make available to its security holders, as soon as reasonably
practicable, an earnings statement covering at least twelve (12) months which
shall satisfy the provisions of Section 11(a) of the 1933 Act and Rule 158
thereunder; and

                  (q) cooperate and assist in the performance of any due
diligence investigation by any Underwriter and its counsel (including any
"qualified independent underwriter" that is required to be retained in
accordance with the rules and regulations of the NASD).

      The Company may (as a condition to such Holder's participation in the
Shelf Registration) require each Holder of Registrable Securities to furnish to
the Company such information regarding such Holder and the proposed distribution
by such Holder of such Registrable Securities as the Company may from time to
time reasonably request in writing. Each Holder further agrees promptly to
furnish to the Company in writing all information required to be disclosed in
order to make the information previously furnished to the Company by such Holder
not misleading in any material respect, any other information regarding such
Holder and the distribution of such Registrable Securities as may be required to
be disclosed in the Registration Statement under applicable law or

                                      -13-
<PAGE>

pursuant to SEC comments and any information otherwise required by the Company
to comply with applicable law or regulations. Each Holder further agrees,
following termination of the Effectiveness Period, to notify the Company, within
seven business days of a request, of the amount of Registrable Securities sold
pursuant to the Registration Statement and, in the absence of a response, the
Company may assume that all of the Holder's Registrable Securities were so sold.

      Each Holder agrees that, upon receipt of any notice from the Company of
the happening of any event or the discovery of any facts, described in Section
3(e)(ii), 3(e)(iii), 3(e)(iv), 3(e)(v) or 3(e)(vi) hereof, such Holder will
forthwith discontinue disposition of Registrable Securities pursuant to a
Registration Statement until receipt by such Holder of (i) the copies of the
supplemented or amended Prospectus contemplated by Section 3(h) hereof or (ii)
written notice from the Company that the Registration Statement is once again
effective or that no supplement or amendment is required. If so directed by the
Company, such Holder will deliver to the Company (at the Company's expense) all
copies in such Holder's possession, other than permanent file copies then in
such Holder's possession, of the Prospectus covering such Registrable Securities
current at the time of receipt of such notice. Nothing in this paragraph shall
prevent the accrual of Liquidated Damages on any Securities.

      If any of the Registrable Securities covered by any Registration Statement
are to be sold in an underwritten offering, the Underwriter or Underwriters and
manager or managers that will manage such offering will be selected by the
Majority Holders of such Registrable Securities included in such offering and
shall be reasonably acceptable to the Company; provided, however, that
notwithstanding anything to the contrary contained in this Agreement, no
underwritten offering shall be effected pursuant to this Agreement without the
prior consent of the Company. No Holder of Registrable Securities may
participate in any underwritten registration hereunder unless such Holder (a)
agrees to sell such Holder's Registrable Securities on the basis provided in any
underwriting arrangements approved by the Persons entitled hereunder to approve
such arrangements, (b) completes and executes all questionnaires, powers of
attorney, indemnities, underwriting agreements and other documents required
under the terms of such underwriting arrangements and (c) provides the Company
with the information required in Section 2.1(d) above.

      4.    Indemnification and Contribution.

                  (a) The Company agrees to indemnify and hold harmless each
Holder, and each Person who participates as an underwriter (each, an
"UNDERWRITER" and collectively, the "UNDERWRITERS") and each Person, if any, who
controls the Holder or Underwriter within the meaning of either Section 15 of
the 1933 Act or Section 20 of the 1934 Act as follows:

                        (i) against any and all loss, liability, claim, damage
and expense whatsoever, as incurred, arising out of any untrue statement or
alleged untrue statement of a material fact contained in any Registration
Statement (or any amendment or supplement thereto, including all documents
incorporated therein by reference therein) pursuant to which Registrable
Securities were registered under the 1933 Act, or any omission or alleged
omission therefrom of a material fact required to be stated therein or necessary
to make the statements therein not misleading, or arising out of any untrue
statement or alleged untrue statement of a material fact contained in any

                                      -14-
<PAGE>

Prospectus (or any amendment or supplement thereto, including all documents
incorporated therein by reference), or any omission or alleged omission
therefrom of a material fact necessary in order to make the statements therein,
in the light of the circumstances under which they were made, not misleading;

                        (ii) against any and all loss, liability, claim, damage
and expense whatsoever, as incurred, to the extent of the aggregate amount paid
in settlement of any litigation, or any investigation or proceeding by any
governmental agency or body, commenced or threatened, or of any claim whatsoever
based upon any such untrue statement or omission, or any such alleged untrue
statement or omission; provided that (subject to Section 4(d) below) any such
settlement is effected with the written consent of the Company; and

                        (iii) against any and all expense whatsoever, as
incurred (including the reasonable fees and disbursements of counsel chosen by
any indemnified party), reasonably incurred in investigating, preparing or
defending against any litigation, or any investigation or proceeding by any
governmental agency or body, commenced or threatened, or any claim whatsoever
based upon any such untrue statement or omission, or any such alleged untrue
statement or omission, to the extent that any such expense is not paid under
subparagraph (i) or (ii) above;

provided, however, that this indemnity provision shall not apply to any loss,
liability, claim, damage or expense to the extent arising out of any untrue
statement or omission or alleged untrue statement or omission made in reliance
upon and in conformity with written information furnished to the Company by or
on behalf of any Holder or Underwriter (or any person who expressly controls
Holder or Underwriter) expressly for use in a Registration Statement (or any
amendment thereto) or any Prospectus (or any amendment or supplement thereto);
provided, further, that this indemnity provision shall not apply to any loss,
liability, claim, damage or expense if the Holder fails to deliver at or prior
to the written confirmation of sale, the most recent Prospectus furnished to
such Holder by the Company and such Prospectus, as amended or supplemented as of
the time of such confirmation of sale, (including any amendment or supplement
filed with the SEC that is incorporated by reference in the Prospectus as of the
time of such confirmation of sale), would have corrected such untrue statement
or omission or alleged untrue statement or omission of a material fact and the
delivery thereof was required by law.

                  (b) Each Holder, severally but not jointly, agrees to
indemnify and hold harmless the Company, each Underwriter and the other selling
Holders, and each of their respective directors and officers, and each Person,
if any, who controls the Company, any Underwriter or any other selling Holder
within the meaning of Section 15 of the 1933 Act or Section 20 of the 1934 Act,
against any and all loss, liability, claim, damage and expense described in the
indemnity contained in Section 4(a) hereof, as incurred, but only with respect
to untrue statements or omissions, or alleged untrue statements or omissions,
made in the Registration Statement (or any amendment thereto) or any Prospectus
included therein (or any amendment or supplement thereto) in reliance upon and
in conformity with written information with respect to such Holder furnished to
the Company by or on behalf of such Holder or any other person who controls such
Holder expressly for use in the Registration Statement (or any amendment
thereto) or such Prospectus (or any amendment or

                                      -15-
<PAGE>

supplement thereto); provided, however, that no such Holder shall be liable for
any claims hereunder in excess of the amount of net proceeds received by such
Holder from the sale of Registrable Securities pursuant to such Registration
Statement.

                  (c) Each indemnified party shall give notice as promptly as
reasonably practicable to each indemnifying party of any action or proceeding
commenced against it in respect of which indemnity may be sought hereunder, but
failure so to notify an indemnifying party shall not relieve such indemnifying
party from any liability hereunder to the extent it is not materially prejudiced
as a result thereof and in any event shall not relieve it from any liability
which it may have otherwise than on account of this indemnity provision. An
indemnifying party may participate at its own expense in the defense of any such
action and, to the extent that it may wish, jointly with any other similarly
notified indemnifying party, to assume the defense thereof with counsel
reasonably satisfactory to the indemnified party; provided, however, that
counsel to the indemnifying party shall not (except with the consent of the
indemnified party) also be counsel to the indemnified party. In no event shall
the indemnifying party or parties be liable for the fees and expenses of more
than one counsel (in addition to any local counsel) separate from their own
counsel for all indemnified parties in connection with any one action or
separate but similar or related actions in the same jurisdiction arising out of
the same general allegations or circumstances. No indemnifying party shall,
without the prior written consent of the indemnified parties, settle or
compromise or consent to the entry of any judgment with respect to any
litigation, or any investigation or proceeding by any governmental agency or
body, commenced or threatened, or any claim whatsoever in respect of which
indemnification or contribution could be sought under this Section 4 (whether or
not the indemnified parties are actual or potential parties thereto), unless
such settlement, compromise or consent (i) includes an unconditional release of
each indemnified party from all liability arising out of such litigation,
investigation, proceeding or claim and (ii) does not include a statement as to
or an admission of fault, culpability or a failure to act by or on behalf of any
indemnified party.

                  (d) If at any time an indemnified party shall have requested
an indemnifying party to reimburse the indemnified party for fees and expenses
of counsel, such indemnifying party agrees that it shall be liable for any
settlement of the nature contemplated by Section 4(a)(ii) hereof effected
without its written consent if (i) such settlement is entered into more than
forty-five (45) days after receipt by such indemnifying party of the aforesaid
request, (ii) such indemnifying party shall have received notice of the terms of
such settlement at least thirty (30) days prior to such settlement being entered
into and (iii) such indemnifying party shall not have reimbursed such
indemnified party in accordance with such request prior to the date of such
settlement.

                  (e) If the indemnification provided for in this Section 4 is
for any reason unavailable to or insufficient to hold harmless an indemnified
party in respect of any losses, liabilities, claims, damages or expenses
referred to therein, then each indemnifying party shall contribute to the
aggregate amount of such losses, liabilities, claims, damages and expenses
incurred by such indemnified party, as incurred, in such proportion as is
appropriate to reflect the relative fault of the indemnifying party or parties,
on the one hand and of the indemnified party or parties, on

                                      -16-
<PAGE>

the other hand, in connection with the statements or omissions that resulted in
such losses, liabilities, claims, damages or expenses, as well as any other
relevant equitable considerations.

      The relative fault of such indemnifying party or parties, on the one hand
and the indemnified party or parties on the other hand shall be determined by
reference to, among other things, whether any such untrue or alleged untrue
statement of a material fact or omission or alleged omission to state a material
fact relates to information supplied by such indemnifying party or parties or
such indemnified party or parties, and the parties' relative intent, knowledge,
access to information and opportunity to correct or prevent such statement or
omission.

                  (f) The Company and the Holders agree that it would not be
just or equitable if contribution pursuant to this Section 4 were determined by
pro rata allocation or by any other method of allocation that does not take
account of the equitable considerations referred to in paragraph (e) above. The
aggregate amount of losses, liabilities, claims, damages and expenses incurred
by an indemnified party and referred to above in this Section 4 shall be deemed
to include any legal or other expenses reasonably incurred by such indemnified
party in investigating, preparing or defending against any litigation, or any
investigation or proceeding by any governmental agency or body, commenced or
threatened, or any claim whatsoever based upon any such untrue or alleged untrue
statement or omission or alleged omission.

      Notwithstanding the provisions of this Section 4, any Holder or
Underwriter shall not be required to contribute any amount in excess of the
amount by which the total price at which Registrable Securities sold by it
pursuant to a Registration Statement were offered exceeds the amount of any
damages that the Holder or Underwriter has otherwise been required to pay by
reason of any such untrue or alleged untrue statement or omission or alleged
omission.

      No Person guilty of fraudulent misrepresentation (within the meaning of
Section 11(f) of the 1933 Act) shall be entitled to contribution from any Person
who was not guilty of such fraudulent misrepresentation.

      For purposes of this Section 4, each Person, if any, who controls any of
the Holder or Underwriter within the meaning of Section 15 of the 1933 Act or
Section 20 of the 1934 Act shall have the same rights to contribution as such
Holder or Underwriter, as the case may be, and each director of the Company,
each officer of the Company who signed the Registration Statement and each
Person, if any, who controls the Company within the meaning of Section 15 of the
1933 Act or Section 20 of the 1934 Act shall have the same rights to
contribution as the Company. The respective obligations of the Holders, and
Underwriters to contribute pursuant to this Section 4 are several in proportion
to the principal amount at maturity of Securities sold by them pursuant to a
Registration Statement and not joint.

      The indemnity and contribution provisions contained in this Section 4
shall remain operative and in full force and effect regardless of (i) any
termination of this Agreement, (ii) any investigation made by or on behalf of
any Holder or Underwriter or any Person controlling any Holder or Underwriter,
or by or on behalf of the Company, its officers, or directors or any Person
controlling the Company and (iii) any sale of Registrable Securities pursuant to
a Registration Statement.

                                      -17-
<PAGE>

      5.    Miscellaneous.

            5.1 Rule 144 and Rule 144A. For so long as the Company is subject to
the reporting requirements of Section 13 or 15 of the 1934 Act, the Company
covenants that it will use its reasonable best efforts to file the reports
required to be filed by it under the 1933 Act and Section 13(a) or 15(d) of the
1934 Act. For so long as any Registrable Securities remain outstanding, if the
Company ceases to be subject to the reporting requirements of Section 13 or 15
of the 1934 Act, it will upon the request of any Holder or beneficial owner of
Registrable Securities (a) make publicly available such information (including,
without limitation, the information specified in Rule 144(c)(2) under the 1933
Act) as is necessary to permit sales pursuant to Rule 144, (b) deliver or cause
to be delivered, promptly following a request by any Holder or beneficial owner
of Registrable Securities or any prospective purchaser or transferee designated
by such Holder or beneficial owner, such information (including, without
limitation, the information specified in Rule 144A(d)(4) under the 1933 Act) as
is necessary to permit sales pursuant to Rule 144A and it will take such further
action as any Holder or beneficial owner of Registrable Securities may
reasonably request, and (c) take such further action that is reasonable under
the circumstances, in each case, to the extent required from time to time to
enable such Holder to sell its Registrable Securities without registration under
the 1933 Act within the limitation of the exemptions provided by (i) Rule 144,
as such Rule may be amended from time to time, (ii) Rule 144A, as such Rule may
be amended from time to time or (iii) any similar rules or regulations hereafter
adopted by the SEC. For so long as any Registrable Securities remain
outstanding, upon the request of any Holder or beneficial owner of Registrable
Securities, the Company will deliver to such Holder a written statement as to
whether it has complied with such requirements.

            5.2 No Inconsistent Agreements. The Company has not entered into nor
will the Company on or after the date of this Agreement enter into any agreement
that is inconsistent with the rights granted to the Holders of Registrable
Securities in this Agreement or otherwise conflicts with the provisions hereof.
The rights granted to the Holders hereunder do not for the term of this
Agreement and will not in any way conflict with and are not and will not be
inconsistent with the rights granted to the holders of any of the Company's
other issued and outstanding securities under any other agreements entered into
by the Company or any of its subsidiaries.

            5.3 Amendments and Waivers. The provisions of this Agreement,
including the provisions of this sentence, may not be amended, modified or
supplemented, and waivers or consents to departures from the provisions hereof
may not be given, unless the Company has obtained the written consent of Holders
of a majority in outstanding Common Stock constituting Registrable Securities
affected by such amendment, modification, supplement, waiver or departure. For
the purpose of the preceding sentence, Holders of Notes shall be deemed to be
Holders of the number of shares of Common Stock into which such Notes are or
would be convertible as of the date on which such consent is requested.
Notwithstanding the foregoing, a waiver or consent to depart from the provisions
hereof with respect to a matter that relates exclusively to the rights of
Holders of Registrable Securities whose securities are being sold pursuant to a
Registration Statement and that does not directly or indirectly affect the
rights of other Holders of Registrable Securities may be given by Holders of at
least a majority of the Registrable Securities being sold by such Holders

                                      -18-
<PAGE>

pursuant to such Registration Statement; provided that the provisions of this
sentence may not be amended, modified, or supplemented except in accordance with
the first sentence of this Section 5.3. Each Holder of Registrable Securities
outstanding at the time of any such amendment, modification, supplement, waiver
or consent or thereafter shall be bound by any such amendment, modification,
supplement, waiver or consent effected pursuant to this Section 5.3, whether or
not any notice, writing or marking indicating such amendment, modification,
supplement, waiver or consent appears on the Registrable Securities or is
delivered to such Holder.

            5.4 Notices. All notices and other communications provided for or
permitted hereunder shall be made in writing by hand delivery, registered
first-class mail, facsimile, or any courier guaranteeing overnight delivery (a)
if to a Holder (other than the Initial Purchaser), at the most current address
set forth on the records of the registrar under the Indenture, (b) if to the
Initial Purchaser, at the most current address given by the Initial Purchaser to
the Company by means of a notice given in accordance with the provisions of this
Section 5.4, which address initially is the address set forth in the Purchase
Agreement with respect to the Initial Purchaser with a copy to Shearman &
Sterling LLP, 1080 Marsh Road, Menlo Park, California 94025, Attention: Bruce
Czachor, (c) if to the Company, initially at the Company's address set forth in
the Purchase Agreement with a copy to Gibson Dunn & Crutcher LLP, One Montgomery
Street, Suite 3100, San Francisco, California 94104, Attention: Gregory J.
Conklin, and thereafter at such other address of which notice is given in
accordance with the provisions of this Section 5.4, and (d) if to any
Underwriter, at the most current address given by such Underwriter to the
Company by means of a notice given in accordance with the provisions of this
Section 5.4, which address initially is the address set forth in the applicable
underwriting agreement.

      All such notices and communications shall be deemed to have been duly
given: at the time of delivery by hand, if delivered by hand; two business days
after being deposited in the mail, postage prepaid, if mailed; when receipt is
acknowledged, if facsimiled; and on the next business day if timely delivered to
an air courier guaranteeing overnight delivery.

      Copies of all such notices, demands or other communications shall be
concurrently delivered by the Person giving the same to the Trustee, at the
address specified in the Indenture.

            5.5 Successors and Assigns. This Agreement shall inure to the
benefit of and be binding upon the successors, assigns and transferees of each
of the parties, including, without limitation and without the need for an
express assignment, subsequent Holders; provided, that (a) this Agreement shall
not inure to the benefit of or be binding upon a successor or assign of a Holder
unless and to the extent such successor or assign acquires Registrable
Securities from a Holder and (b) nothing herein shall be deemed to permit any
assignment, transfer or other disposition of Registrable Securities in violation
of the terms hereof or of the Purchase Agreement or the Indenture. If any
transferee of any Holder shall acquire Registrable Securities, in any manner,
whether by operation of law or otherwise, such Registrable Securities shall be
held subject to all of the terms of this Agreement, and by taking and holding
such Registrable Securities, such Person shall be conclusively deemed to have
agreed to be bound by and to perform all of the terms and

                                      -19-
<PAGE>

provisions of this Agreement, including the restrictions on resale set forth in
this Agreement and, if applicable, the Purchase Agreement, and such person shall
be entitled to receive the benefits hereof.

            5.6 Third Party Beneficiaries. The Initial Purchaser (even if such
Initial Purchaser is not a Holder of Registrable Securities) shall be a third
party beneficiary of the agreements made hereunder between the Company, on the
one hand, and the Holders, on the other hand, and shall have the right to
enforce such agreements directly to the extent it deems such enforcement
necessary or advisable to protect its rights or the rights of Holders hereunder.
Each Holder of Registrable Securities shall be a third party beneficiary to the
agreements made hereunder between the Company, on the one hand, and the Initial
Purchaser, on the other hand, and shall have the right to enforce such
agreements directly to the extent it deems such enforcement necessary or
advisable to protect its rights hereunder.

            5.7 Restrictions on Resales Until the expiration of two years after
the original issuance of the Securities, the Company will not, and will use its
reasonable best efforts to ensure that its "affiliates" (as such term is defined
in Rule 144(a)(1) under the 1933 Act) do not, resell any Securities which are
"restricted securities" (as such term is defined under Rule 144(a)(3) under the
1933 Act) that have been reacquired by any of them and shall immediately upon
any purchase of any such Securities submit such Securities to the Trustee for
cancellation.

            5.8 Headings. The headings in this Agreement are for convenience of
reference only and shall not limit or otherwise affect the meaning hereof.

            5.9 Severability. In the event that any one or more of the
provisions contained herein, or the application thereof in any circumstance, is
held invalid, illegal or unenforceable, the validity, legality and
enforceability of any such provision in every other respect and of the remaining
provisions contained herein shall not be affected or impaired thereby.

            5.10 GOVERNING LAW. THIS AGREEMENT SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.

            5.11 Counterparts. This Agreement may be executed by facsimile in
any number of counterparts and by the parties hereto in separate counterparts,
each of which when so executed shall be deemed to be an original and all of
which taken together shall constitute one and the same agreement.

            5.12 Entire Agreement. This Agreement is intended by the parties
hereto as a final expression of their agreement and is intended to be a complete
and exclusive statement of the agreement and understanding of the parties hereto
in respect of the subject matter contained herein and the registration rights
granted by the Company with respect to the Registrable Securities. Except as
provided in the Purchase Agreement, there are no restrictions, promises,
warranties or undertakings, other than those set forth or referred to herein,
with respect to the registration rights granted by the Company with respect to
the Registrable Securities. This Agreement supersedes all prior agreements and
undertakings among the parties hereto with respect to such registration rights.

                                      -20-
<PAGE>

      IN WITNESS WHEREOF, the parties have executed this Agreement as of the
date first written above.

                                                 Thoratec Corporation

                                                 By: /s/ D. Keith Grossman
                                                     ------------------------
                                                 Name: D. Keith Grossman
                                                 Title:President and Chief
                                                        Executive Officer

             [Signature page to the Registration Rights Agreement]
<PAGE>


CONFIRMED AND ACCEPTED, as of
      the date first above written:

MERRILL LYNCH & CO.
MERRILL LYNCH, PIERCE, FENNER & SMITH
               INCORPORATED

By:  /s/ Edward D. Bail
     -----------------------------------
        Authorized Signatory

             [Signature page to the Registration Rights Agreement]