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                                                                     EXHIBIT 4.3

                               MICRUS CORPORATION

                  AMENDED AND RESTATED STOCKHOLDERS' AGREEMENT

      THIS AMENDED AND RESTATED STOCKHOLDERS' AGREEMENT is made as of February
21, 2005 (this "Agreement") by and among Micrus Corporation, a Delaware
corporation (the "Company"), J. Todd Derbin ("Derbin"), Joseph A. Horton M.D.
("Horton", and together with Derbin, the "Founders") and the individuals and
entities listed on the signature pages of this Agreement (collectively, the
"Investors", and together with the Founders and the permitted assignees of the
Founders and Investors, the "Stockholders") and amends and restates in its
entirety the Amended and Restated Stockholders Agreement dated June 10, 2003
(the "Previous Stockholders' Agreement").

                                   BACKGROUND

      Each of the Stockholders owns shares of Common Stock and/or Preferred
Stock (together with any other shares of capital stock of the Company now owned
or hereafter acquired by the Stockholders and their successors or assigns from
any Person by any means, including without limitation, any acquisition by gift,
purchase, dividend, conversion, stock split, recapitalization or otherwise,
collectively, the "Shares") and/or warrants to purchase Shares (the "Warrants").
It is deemed to be in the best interest of the Company and the Stockholders that
provision be made for the continuity and stability of the business and policies
of the Company and, to that end, the Company and the Stockholders hereby set
forth their agreement with respect to the Shares.

      NOW, THEREFORE, in consideration of the premises and of the mutual
consents and obligations hereinafter set forth, the parties hereto hereby agree
as follows:

      A. Amendment of Previous Stockholders' Agreement; Waiver of Right of First
Offer. Effective and contingent upon execution of this Agreement by the Company
and the holders of (a) at least sixty-six and 67/100 percent (66.67%) of the
shares of Preferred Stock (or shares of Common Stock issued upon conversion
thereof) held by all Stockholders, and (b) the Stockholders holding a majority
of the shares of Common Stock (other than those shares specified in subparagraph
(a) immediately above, and upon closing of the transactions contemplated by that
certain Series E Preferred Stock and Warrant Purchase Agreement dated on or
about the date hereof (the "Purchase Agreement"), the Previous Stockholders'
Agreement is hereby amended and restated in its entirety to read as set forth in
this Agreement, and the Company and the Stockholders hereby agree to be bound by
the provisions hereof as the sole agreement of the Company and the Stockholders
with respect to registration rights of the Company's securities and certain
other rights, as set forth herein. THE STOCKHOLDERS THAT ARE MAJOR INVESTORS (AS
THAT TERM IS DEFINED IN THE PREVIOUS STOCKHOLDERS' AGREEMENT) HEREBY WAIVE THE
RIGHT OF FIRST OFFER, INCLUDING THE NOTICE REQUIREMENTS, SET FORTH IN THE
PREVIOUS STOCKHOLDERS' AGREEMENT WITH RESPECT TO THE ISSUANCE OF

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SERIES E PREFERRED STOCK AND WARRANTS TO PURCHASE COMMON STOCK ISSUED PURSUANT
TO THE PURCHASER AGREEMENT.

      1. Definitions. All capitalized terms used in this Agreement shall have
the meanings assigned to them elsewhere in this Agreement or as specified below:

            "Affiliate" of any Person shall mean any Person (i) directly or
indirectly controlling, controlled by or under common control with such Person
or (ii) each of such Person's officers, director, joint venturers, members or
partners.

            "Closing" shall mean the first closing of the transactions
contemplated under the Purchase Agreement.

            "Closing Date" shall mean the date on which the Closing under the
Purchase Agreement occurs.

            "Commission" shall mean the United States Securities and Exchange
Commission.

            "Common Stock" shall mean (a) the Company's Class A Common Stock,
par value $0.01 per share, as authorized on the date of this Agreement, (b) the
Company's Class B Common Stock, par value $0.01 per share, as authorized on the
date of this Agreement, (c) any other capital stock of any class or classes
(however designated) of the Company, authorized on or after the date hereof, the
holders of which shall have the right, without limitation as to amount, either
to all or to a share of the balance of current dividends and liquidating
distributions after the payment of dividends and distributions on any shares
entitled to preference under the Restated Certificate of Incorporation (as the
same may be further amended from time to time after the Closing), and (d) any
other securities into which or for which any of the securities described in
clause (a), (b) or (c) of this definition may be converted or exchanged pursuant
to a plan of recapitalization, reorganization, merger, sale of assets or
otherwise.

            "Company Notice" shall have the meaning set forth in Section 3(b)
hereof.

            "Designated Offering" shall have the meaning set forth in the
Restated Certificate of Incorporation.

            "Equity Securities" shall have the meaning set forth in Section 2(a)
hereof.

            "Exchange Act" shall mean the Securities Exchange Act of 1934, as
amended, and the rules and regulations of the Commission promulgated thereunder,
all as the same shall be in effect at the time.

            "Exchange Act Registration Statement" shall mean a registration
statement filed pursuant to the Exchange Act, relating to any class of equity
securities of the Company.

            "Excluded Form" shall mean a registration statement filed pursuant
to the Securities Act on Form S-8, S-4 or any similar or successor forms.

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            "Excluded Securities" shall mean those securities described in
Section 2(f) hereof.

            "Founders Notice" shall have the meaning set forth in Section 3(c)
hereof.

            "Form S-3" shall mean such form under the Securities Act as is in
effect on the date hereof or any successor registration form under the
Securities Act subsequently adopted by the Commission which permits inclusion or
incorporation of substantial information by reference to other documents filed
by the Company with the Commission.

            "Holder" shall mean any holder of Preferred Stock, Warrants or Class
B Common Stock owning of record Registrable Securities that have not been sold
to the public and, for purposes of this Agreement, a record holder of shares of
Preferred Stock, Warrants or Class B Common Stock convertible into such
Registrable Securities shall be deemed to be the Holder of such Registrable
Securities; provided, however, that the Company shall in no event be obligated
to register the Preferred Stock, Warrants or Class B Common Stock, and that
Holders of Registrable Securities shall not be required to convert their shares
of Preferred Stock or Class B Common Stock into Class A Common Stock or exercise
any Warrants in order to exercise the registration rights granted under Section
4 hereof, until immediately before the closing of the offering to which the
registration relates.

            "Investor Oversubscription Rights" shall have the meaning set forth
in Section 2(b) hereof.

            "Major Investors" shall have the meaning set forth in Section 2
hereof.

            "Notice of Acceptance" shall have the meaning set forth in Section
2(c) hereof.

            "Offer" shall have the meaning set forth in Section 2(a) hereof.

            "Oversubscribing Investor" shall have the meaning set forth in
Section 2(b) hereof.

            "Permitted Transfer" and "Permitted Transferee" shall have the
meanings set forth in Section 3(d) hereof.

            "Person" shall mean and include an individual, a corporation, a
partnership, a trust, an unincorporated organization and a government or any
department, agency or political subdivision thereof.

            "Preferred Stock" shall mean the Series A Preferred Stock, the
Series B Preferred Stock, the Series C Preferred Stock, the Series D Preferred
Stock, the Series D-1 Preferred Stock, the Series D-2 Preferred Stock, the
Series D-3 Preferred Stock, and the Series E Preferred Stock.

            "Purchase Agreement" shall mean the Micrus Corporation Series E
Preferred Stock and Warrant Purchase Agreement dated on or about the date
hereof, between the Company and certain Investors, as the same may be amended
from time to time.

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            "Register", "registered" and "registration" shall refer to a
registration effected by preparing and filing a registration statement in
compliance with the Securities Act, and the declaration or ordering of
effectiveness of such registration statement.

            "Registrable Securities" shall mean: (a) all the shares of Class A
Common Stock of the Company issued or issuable upon the conversion of the shares
of Series A Preferred Stock, Series B Preferred Stock, Series C Preferred Stock,
Series D Preferred Stock, Series D-2 Preferred Stock, Series D-3 Preferred
Stock, Series E Preferred Stock and Class B Common Stock that are now owned or
may hereafter be acquired by any Holder or its permitted successors and assigns,
(b) all the shares of Class A Common Stock of the Company issued or issuable
upon the exercise of the Warrants, and (c) any shares of Common Stock of the
Company issued as (or issuable upon the conversion or exercise of any warrant,
right or other security which is issued as) a dividend or other distribution
with respect to, or in exchange for or in replacement of all such shares of
Common Stock described in clause (a) of this definition; excluding in all cases,
however, (i) any Registrable Securities sold pursuant to registration under the
Securities Act or (ii) any Registrable Securities sold, subsequent to the
Company's initial public offering of securities registered under the Securities
Act, pursuant to Rule 144 (or similar or successor rule) promulgated under the
Securities Act.

            "Registrable Securities then outstanding" shall mean the number of
shares of Registrable Securities that are then issued and outstanding or are
then issuable pursuant to the exercise or conversion of then outstanding and
then exercisable options, warrants or other convertible securities.

            "Remaining Securities" shall have the meaning set forth in Section
2(d) hereof.

            "Restated Certificate of Incorporation" shall mean the Company's
Eleventh Amended and Restated Certificate of Incorporation setting forth the
designations, rights, preferences and privileges and qualifications, limitations
and restrictions of Common Stock and Preferred Stock, filed in the Office of the
Secretary of State of Delaware.

            "Sale Shares" shall have the meaning set forth in Section 3(a)
hereof.

            "Securities Act" shall mean the Securities Act of 1933, as amended,
and the rules and regulations of the Commission promulgated thereunder, all as
the same shall be in effect at the time.

            "Series A Preferred Stock" shall mean the Company's authorized
shares of Series A Convertible Preferred Stock, par value $.01 per share, having
the designations, rights, preferences and privileges and qualifications,
limitations and restrictions of preferred stock set forth in the Restated
Certificate of Incorporation.

            "Series B Preferred Stock" shall mean the Company's authorized
shares of Series B Convertible Preferred Stock, par value $.01 per share, having
the designations, rights, preferences and privileges and qualifications,
limitations and restrictions of preferred stock set forth in the Restated
Certificate of Incorporation.

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            "Series C Preferred Stock" shall mean the Company's authorized
shares of Series C Convertible Preferred Stock, par value $.01 per share, having
the designations, rights, preferences and privileges and qualifications,
limitations and restrictions of preferred stock set forth in the Restated
Certificate of Incorporation.

            "Series D Preferred Stock" shall mean the Company's authorized
shares of Series D Convertible Preferred Stock, par value $.01 per share, having
the designations, rights, preferences and privileges and qualifications,
limitations and restrictions of preferred stock set forth in the Restated
Certificate of Incorporation.

            "Series D-1 Preferred Stock" shall mean the Company's authorized
shares of Series D-1 Non-Voting Convertible Preferred Stock, par value $.01 per
share, having the designations, rights, preferences and privileges and
qualifications, limitations and restrictions of preferred stock set forth in the
Restated Certificate of Incorporation.

            "Series D-2 Preferred Stock" shall mean the Company's authorized
shares of Series D-2 Convertible Preferred Stock, par value $.01 per share,
having the designations, rights, preferences and privileges and qualifications,
limitations and restrictions of preferred stock set forth in the Restated
Certificate of Incorporation.

            "Series D-3 Preferred Stock" shall mean the Company's authorized
shares of Series D-3 Convertible Preferred Stock, par value $.01 per share,
having the designations, rights, preferences and privileges and qualifications,
limitations and restrictions of preferred stock set forth in the Restated
Certificate of Incorporation.

            "Series E Preferred Stock" shall mean the Company's authorized
shares of Series E Convertible Preferred Stock, par value $.01 per share, having
the designations, rights, preferences and privileges and qualifications,
limitations and restrictions of preferred stock set forth in the Restated
Certificate of Incorporation.

            "Shares Transfer" shall have the meaning set forth in Section 3(a)
hereof.

            "Transfer" shall mean any sale, assignment, transfer, disposition,
donation, pledge, bequest, hypothecation, gift, conveyance, encumbrance or any
other disposition or transfer of a Share or any interest or rights (legal or
equitable) therein by any means whatsoever, whether direct or indirect, absolute
or conditional, voluntary or involuntary, by operation of law (including without
limitation, by operation of the laws of descent and distribution) or otherwise.

            "Transferring Stockholder" shall have the meaning set forth in
Section 3(a) hereof.

            "TS Notice" shall have the meaning set forth in Section 3(a) hereof.

            "Violation" shall have the meaning set forth in Section 4(h)(i)
hereof.

      2. Right of First Offer. Each Investor who continues, directly or through
one or more Affiliates, to hold either (i) ten (10%) percent or more of any
series (other than Series E Preferred

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Stock) of the issued and outstanding shares of Preferred Stock; or (ii) at least
200,000 shares of Series E Preferred Stock (appropriately adjusted for any stock
split, dividend, combination or other recapitalization) (each such Investor, a
"Major Investor") shall be entitled to the following right of first offer:

            (a) Except in the case of Excluded Securities, the Company shall not
issue, sell or exchange, agree to issue, sell or exchange, or reserve or set
aside for issuance, sale or exchange, (i) any shares of Common Stock, (ii) any
other equity security of the Company, (iii) any debt security of the Company
which by its terms is convertible into or exchangeable for, with or without
consideration, any equity security of the Company, (iv) any security of the
Company that is a combination of debt and equity or (v) any option, warrant or
other right to subscribe for, purchase or otherwise acquire any equity security
or any such debt security of the Company (collectively, the "Equity
Securities"), unless in each case the Company shall have first offered to sell
to each Major Investor their pro rata share of the Equity Securities, at a price
and on such other terms as shall have been specified by the Company in writing
delivered to the Major Investors (the "Offer"), which Offer by its terms shall
remain open and irrevocable for a period of thirty (30) days from the date the
Offer is received by the Major Investors.

            (b) Each Major Investor shall have the right to purchase up to their
pro rata share of the Equity Securities. As used in this Section 2, a Major
Investor's "pro rata share" shall be that amount of the Equity Securities which
would result in the Major Investor's owning the same percentage of the Company's
issued and outstanding Common Stock after the issuance of Equity Securities as
the Major Investor owned immediately prior to the issuance (assuming in each
case the issuance of all shares issuable upon the conversion of the shares of
Preferred Stock, if any, held by the Investors and upon conversion of the Equity
Securities). However, each Major Investor may, in his notice, subscribe for any
number of the Equity Securities being offered by the Company. Any Equity
Securities which are not purchased by a Major Investor may be purchased by the
other Major Investors ("Oversubscribing Investors") who indicated the desire to
purchase more (specifying the number of shares) than their pro rata share of the
remaining Equity Securities in their respective notices of exercise ("Investor
Oversubscription Rights"). If not enough remaining Equity Securities are offered
for sale to satisfy all properly exercised Investor Oversubscription Rights, the
remaining Equity Securities shall be sold to and purchased by Major Investors
exercising Investor Oversubscription Rights pro rata. For the purpose of
Investor Oversubscription Rights each Oversubscribing Investor's pro rata
portion will be equal to the total number of shares of Common Stock held by such
Oversubscribing Investor (assuming in each case the issuance of all shares
issuable upon the conversion of the shares of Preferred Stock held by the
Investors) as a percentage of the total number of shares of Common Stock held by
all Oversubscribing Investors.

            (c) Notice of a Major Investor's intention to accept, in whole or in
part, an Offer shall be evidenced by a writing signed by the Major Investor and
delivered to the Company at or prior to the end of the 30-day period commencing
with the date the Offer is received by the Major Investor (or, if later, within
10 days after the giving of any written notice of a material change in such
Offer), setting forth such portion (specifying number of shares, principal
amount or the like) of the Equity Securities as the Major Investor elects to
purchase (the "Notice of Acceptance").

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            (d) The Company shall have 90 days from the expiration of the
foregoing 30-day period to sell all or any part of such Equity Securities as to
which a Notice of Acceptance has not been given by the Major Investors (the
"Remaining Securities") to any other Person or Persons, but only upon terms and
conditions which are no more favorable, in the aggregate, to such other Person
or Persons or less favorable to Company than those set forth in the Offer. Upon
the closing of the sale to such other Person or Persons of all the Remaining
Securities, which shall include payment of the purchase price to the Company in
accordance with the terms of the Offer, if a Major Investor has timely submitted
a Notice of Acceptance, he shall purchase from the Company, and the Company
shall sell to the Major Investor, the Equity Securities in respect of which a
Notice of Acceptance was delivered to the Company by the Major Investor, at the
terms specified in the Offer.

            (e) In each case, any Equity Securities not purchased by a Major
Investor or by a Person or Persons in accordance with Section 2(d) may not be
sold or otherwise disposed of until they are again offered to the Major
Investors under the procedures specified in Sections 2(a), (b), (c) and (d)
hereof.

            (f) The rights of the Major Investors under this Section 2 shall not
apply to the following securities (the "Excluded Securities"):

                  (i) Common Stock or options to purchase shares of Common
Stock, issued to officers, employees or directors of, or consultants to, the
Company, pursuant to any agreement, plan or arrangement approved by the Board of
Directors of the Company;

                  (ii) Common Stock issued as a stock dividend or upon any stock
split or other subdivision or combination of shares of Common Stock;

                  (iii) Common Stock issued upon conversion of any shares of
Preferred Stock or Class B Common Stock;

                  (iv) any securities issued for consideration other than cash
pursuant to a merger, consolidation, acquisition or similar business
combination;

                  (v) Common Stock issued in connection with a public offering;

                  (vi) Series E Preferred Stock and warrants to purchase Common
Stock issued pursuant to the Purchase Agreement; and

                  (vii) Common Stock issued upon the exercise of any warrants
outstanding as of the date hereof or issued in connection with the sale of
Series E Preferred Stock.

            (g) Notwithstanding the foregoing provisions of this Section 2, the
rights of the Major Investors and the obligations of the Company under this
Section 2 shall terminate: (i) as to all Major Investors, upon the consummation
of a Designated Offering; and (ii) as to a particular Major Investor, when such
Investor ceases, directly or through one or more Affiliates, to satisfy the
definition of Major Investor set forth above.

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            3. Right of First Refusal. The Founders shall be entitled to the
      following right of first refusal:

            (a) Transfer of Shares. An Investor shall not transfer (each, a
"Transferring Stockholder") any or all of the Shares or any right or interest
therein then owned by him (each, a "Shares Transfer") except by a transfer that
meets the requirements of this Section 3 and of this Agreement generally. If a
Transferring Stockholder proposes to effect a Shares Transfer, whether
voluntarily or involuntarily, then at least ninety (90) days prior to any Shares
Transfer, other than a Permitted Transfer, such Transferring Stockholder shall
give notice (the "TS Notice") to the Company and the Founders of his intention
to effect the Shares Transfer. The TS Notice shall set forth (i) the number,
class and series of shares to be sold by the Transferring Stockholder (the "Sale
Shares"), (ii) the date or proposed date of the Shares Transfer and the name and
address of the proposed transferee, (iii) the principal terms of the Shares
Transfer, including the cash or other property or consideration to be received
upon such Shares Transfer, and (iv) the percentage which the number of Sale
Shares constitutes with respect to the aggregate number of Shares then held by
the Transferring Stockholder. In the case of a proposed transfer by way of gift
or if the nature of the transfer is such that no readily determinable
consideration is to be paid for the transfer of the Sale Shares, then a bona
fide transfer price for purposes of this Section 3(a) shall be determined by the
Board of Directors of the Company promptly upon the Company's receipt of, and as
of the date of, the TS Notice.

            (b) Company's Option. The Company shall have the option, but not the
obligation, to purchase any or all of the Sale Shares on the same terms as
specified in the TS Notice. Within thirty (30) days after the receipt of the TS
Notice, the Company shall give written notice to the Transferring Stockholder
and the Founders (the "Company Notice") stating whether or not it elects to
exercise its option to purchase, the number of Sales Shares, if any, it elects
to purchase, and a date and time for consummation of the purchase not more than
ninety (90) days after the receipt of the Company Notice by the Transferring
Stockholder. Failure by the Company to give such notice within such time period
shall be deemed an election by it not to exercise its option. The Transferring
Stockholder shall not be entitled to vote, either as a stockholder or a director
(if applicable), in connection with the decision of the Company whether to
exercise its option to purchase the Sale Shares, provided, that, if his vote is
required for valid corporate action, then he shall vote in accordance with the
decision of the majority of the other directors or stockholders, as the case may
be.

            (c) Founders' Option. If the Company fails to exercise its right to
purchase under subparagraph (b) hereof, or exercises its right to purchase for
less than all of the Sale Shares, then the Founders shall each have the option,
but not the obligation, to purchase up to their pro rata share of any or all of
the remaining Sale Shares on the same terms as specified in the TS Notice. Each
Founder's pro rata portion of the remaining Sale Shares will be equal to the
total number of shares of Common Stock held by such Founder as a percentage of
the total number of shares of Common Stock held by both Founders. Not later than
thirty (30) days after the Founders receive the Company Notice, each Founder
shall give written notice to the Transferring Stockholder and the Company (the
"Founders Notice") stating whether or not they elect to exercise their option to
purchase, the number of the remaining Sales Shares, if any, they elect to
purchase, and a date and time for consummation

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of the purchase not more than sixty (60) days after the receipt of the Founders
Notice by the Transferring Stockholder. Failure by a Founder to give such notice
within such time period shall be deemed an election by him not to exercise his
option. If a Founder elects not to purchase all of his pro rata share of the
remaining Sale Shares, then the other Founder shall have the right to purchase
any or all such remaining Sale Shares. If the Company and the Founders exercise
their respective rights to purchase less than all the Sale Shares, then the
Transferring Stockholder shall thereafter be free to transfer the remaining Sale
Shares on the terms provided in the Notice (subject to the provisions of Section
4); provided, however, that the Sale Shares shall continue to be subject to the
terms of this Agreement and any such transferee shall agree in writing to be
bound by the obligations imposed upon Stockholders under this Agreement as if
such transferee were originally a signatory to this Agreement.

            (d) Definitions. For purposes of this Agreement, the term "Permitted
Transfer" shall mean a Shares Transfer to an Affiliate, spouse (other than
pursuant to any divorce or separation proceedings or settlement), parents,
children (natural or adopted), stepchildren or grandchildren or a trust for any
of their benefit in the case of a Transferring Stockholder that is an individual
(each recipient being a "Permitted Transferee"); provided, however, that prior
to such Shares Transfer, such Permitted Transferee shall agree in writing to be
bound by the obligations imposed upon Stockholders under this Agreement as if
such transferee were originally a signatory to this Agreement and shall
thereafter be a "Stockholder" hereunder.

            (e) Application of Provisions. In each case, any Sale Shares not
purchased by the proposed transferee in accordance with Section 3(c) hereof may
not be sold or otherwise disposed of until they are again offered to the Company
and the Founders under the procedures specified in Sections 3(a), (b) and (c)
hereof.

            (f) Transfers Void. Any attempted transfer in violation of the terms
of this Section 3 shall be ineffective to vest in any transferee any interest
held by the Transferring Stockholder in the Shares. Without limiting the
foregoing, any purported Shares Transfer in violation hereof shall be
ineffective as against the Company and the Founders, and the Company and the
Founders shall have a continuing right and option (but not an obligation), until
the restrictions contained in this Section 3 terminate, to purchase the shares
purported to be transferred by the Transferring Stockholders for a price and on
terms the same as those at which the purported Shares Transfer was effected.

            (g) Termination of Restrictions. The restrictions in this Section 3
shall terminate upon the consummation of a Designated Offering.

            4. Transfer of Securities; Registration Rights.

            (a) Restriction on Transfer. The Shares shall not be transferable
except upon the conditions specified in this Section 4, which conditions are
intended to ensure compliance with the provisions of the Securities Act and
applicable state securities laws in respect of the transfer thereof.

            (b) Restrictive Legend. Each certificate for the Shares and each
certificate for any such securities issued to subsequent transferees of any such
certificate shall (unless otherwise

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permitted by the provisions of Section 4(c)) be stamped or otherwise imprinted
with the following legend:

      "THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE BEEN ACQUIRED FOR
      INVESTMENT AND HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933,
      AS AMENDED, OR ANY APPLICABLE STATE SECURITIES LAW. THESE SECURITIES MAY
      NOT BE SOLD OR TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR AN
      EXEMPTION THEREFROM UNDER SAID ACT. ADDITIONALLY, THE TRANSFER OF THESE
      SECURITIES IS SUBJECT TO THE CONDITIONS SPECIFIED IN THE AMENDED AND
      RESTATED STOCKHOLDERS' AGREEMENT, AMONG MICRUS CORPORATION AND CERTAIN
      OTHER SIGNATORIES THERETO (AS THE SAME MAY BE AMENDED FROM TIME TO TIME)
      AND NO TRANSFER OF THESE SECURITIES SHALL BE VALID OR EFFECTIVE UNTIL SUCH
      CONDITIONS HAVE BEEN FULFILLED. UPON THE FULFILLMENT OF CERTAIN OF SUCH
      CONDITIONS, MICRUS CORPORATION HAS AGREED TO DELIVER TO THE HOLDER HEREOF
      A NEW CERTIFICATE, NOT BEARING THIS LEGEND, FOR THE SECURITIES REPRESENTED
      HEREBY REGISTERED IN THE NAME OF THE HOLDER HEREOF. COPIES OF SUCH
      AGREEMENT MAY BE OBTAINED AT NO COST BY WRITTEN REQUEST MADE BY THE HOLDER
      OF RECORD OF THIS CERTIFICATE TO THE SECRETARY OF MICRUS CORPORATION."

            In addition, certificate(s) for the Shares may bear other legends as
      may be required by applicable State securities laws or by Regulation S
      under the Securities Act of 1933, as amended.

            (c) Notice of Transfer. The holder of any Shares, by acceptance
thereof agrees, prior to any transfer thereof, to give written notice to the
Company of such holder's intention to effect such transfer and to comply in all
other respects with the provisions of this Section 4(c) and the other applicable
provisions of this Agreement. Each such notice shall describe the manner and
circumstances of the proposed transfer and shall be accompanied by (i) the
written opinion, addressed to the Company, of counsel for the holder of such
Shares, as to whether in the opinion of such counsel (which counsel shall be
reasonably satisfactory to counsel to the Company) such proposed transfer
involves a transaction requiring registration of such shares under the
Securities Act, and (ii) in the case of Registrable Securities, if in the
opinion of such counsel such registration is required, a written request
addressed to the Company by the Holder of Registrable Securities, describing in
detail the proposed method of disposition and requesting the Company to effect
the registration of such Registrable Securities pursuant to the terms and
conditions of Sections 4(d) or 4(e), as the case may be; provided, however, that
no such opinion shall be required in the case of a transfer by any Holder of
Registrable Securities (A) which is a (1) partnership to a partner of such
Holder, or a retired partner of such Holder who retires after the date hereof,
or the estate of any such partner or retired partner, or (2) Person to any
Affiliate of such Person, including without limitation, any officer, director or
stockholder of such corporation, and the transferee agrees in writing to be

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subject to the terms of this Section 4 to the same extent as if such transferee
were originally a signatory to this Agreement or (B) in connection with a
transaction complying with the requirements of Rule 144 (as amended from time to
time) promulgated under the Securities Act (or successor rule thereto). If in
such opinion of counsel the proposed transfer may be effected without
registration under the Securities Act, the holder shall thereupon be entitled to
transfer the Shares in accordance with the terms of the notice delivered by it
to the Company, subject to the other requirements of this Agreement. Each
certificate or other instrument evidencing the securities issued upon the
transfer of any Shares (and each certificate or other instrument evidencing any
untransferred balance of such securities) shall bear the legend set forth in
Section 4(b) unless (x) in such opinion of counsel registration of future
transfer is not required by the applicable provisions of the Securities Act or
(y) the Company shall have waived the requirement of such legend; provided,
however, that such legend shall not be required (1) on any certificate or other
instrument evidencing the securities issued upon such transfer in the event such
transfer shall be made in compliance with the requirements of Rule 144 (as
amended from time to time) promulgated under the Securities Act (or successor
rule thereto) or (2) on any certificate or other instrument which is immediately
resalable (whether or not such resale is proposed) under Rule 144(k) or
successor thereto.

            (d) Piggyback Registrations.

                  (i) The Company shall notify all Holders of Registrable
Securities in writing at least thirty (30) days prior to filing any registration
statement under the Securities Act for purposes of effecting a public offering
of securities of the Company (including, but not limited to, registration
statements relating to secondary offerings of securities of the Company, but
excluding registration statements on an Excluded Form or relating to any
employee benefit plan or a corporate reorganization) and shall afford each such
Holder an opportunity to include in such registration statement all or any part
of the Registrable Securities then held by such Holder. Each Holder desiring to
include in any such registration statement all or any part of the Registrable
Securities held by such Holder shall, within twenty (20) days after receipt of
the above-described notice from the Company, so notify the Company in writing,
and in such notice shall inform the Company of the number of Registrable
Securities such Holder wishes to include in such registration statement. If a
Holder decides not to include all of its Registrable Securities in any
registration statement thereafter filed by the Company, such Holder shall
nevertheless continue to have the right to include any Registrable Securities in
any subsequent registration statement or registration statements as may be filed
by the Company with respect to subsequent offerings of its securities, all upon
the terms and conditions set forth herein.

                  (ii) If the registration statement under which the Company
gives notice under this Section 4(d) is for an underwritten offering, the
Company shall so advise the Holders of Registrable Securities. In such event,
the right of any such Holder to include their Registrable Securities in a
registration pursuant to this Section 4(d) shall be conditioned upon such
Holder's participation in such underwriting and the inclusion of such Holder's
Registrable Securities in the underwriting to the extent provided herein. All
Holders proposing to distribute their Registrable Securities through such
underwriting shall enter into an underwriting agreement in such customary form
with the managing underwriter or underwriters selected by the Company for such
underwriting. Notwithstanding any other provision of this Agreement, if the
managing underwriter(s) determine(s)

                                       11
<PAGE>

in good faith that marketing factors require a limitation of the number of
shares to be underwritten, the number of shares that may be included in said
underwriting shall be allocated, first, to the Company, and second, to each of
the Holders requesting inclusion of their Registrable Securities in such
registration statement on a pro rata basis based on the total number of
Registrable Securities held by each such Holder. If any Holder disapproves of
the terms of any such underwriting, such Holder may elect to withdraw therefrom
by written notice to the Company and the underwriter, delivered at least five
(5) business days prior to the effective date of the registration statement. Any
Registrable Securities excluded or withdrawn from such underwriting shall be
excluded and withdrawn from the registration.

                  (iii) All registration expenses incurred in connection with a
registration pursuant to this Section 4(d) (other than underwriters' discounts
and commissions which shall be borne proportionately by Holders participating in
a registration pursuant to this Section 4(d)) shall be borne by the Company,
including the reasonable fees and expenses of a single special counsel for the
holders of the Series E Preferred Stock (which shall be borne by the Company).

            (e) Form S-3 Registration. In case the Company receives from the
Holders of at least fifty percent (50%) of the Registrable Securities held by
all Holders, a written request or requests that the Company effect a
registration on Form S-3 and any related qualification or compliance with
respect to all or part of the Registrable Securities owned by such Holders, then
the Company shall:

                  (i) Promptly give written notice of the proposed registration
and the Holders' request therefor, and any related qualification or compliance,
to all Holders of Registrable Securities; and

                  (ii) As soon as practicable, effect such registration and all
such qualifications and compliances as may be so requested and as would permit
or facilitate the sale and distribution of all or such portion of such Holders'
Registrable Securities as are specified in such request, together with all or
such portion of the Registrable Securities of any other Holder or Holders
joining in such request as are specified in a written request given within
twenty (20) days after receipt of such written notice from the Company;
provided, however, that the Company shall not be obligated to effect any such
registration, qualification or compliance pursuant to this Section 4(e): (A) if
Form S-3 is not available for such offering by the Holders; (B) if the Holders
propose to sell Registrable Securities at an aggregate gross offering price to
the public of less than $1,000,000.00; (C) if the Company has, within the six
(6) -month period preceding the date of such request, already effected one
registration on Form S-3 for the Holders pursuant to this Section 4(e); (D) if
the Company furnished to the holders of Registerable Securities a certificate
signed by the President or Chief Executive Officer of the Company stating that
in the good faith judgment of the Board of Directors of the Company, it would be
detrimental to the Company and its stockholders for such Form S-3 registration
statement to be filed at such time, in which event the Company shall have the
right to defer the filing of the Form S-3 registration statement for a period of
not more than 120 days after receipt of the request of the holders of
Registerable Securities under this Section 4(e); or (E) in any particular
jurisdiction in which the Company would be required to qualify to do business or
to execute a general consent to service of process in effecting such
registration, qualification or compliance.

                                       12
<PAGE>

                  (iii) Subject to the foregoing, the Company shall file a Form
S-3 registration statement covering the Registrable Securities to be registered
pursuant to this Section 4(e) as soon as practicable after receipt of the
request or requests of the Holders for such registration. All registration
expenses incurred in connection with a registration pursuant to this Section
4(e) (other than underwriters' discounts and commissions which shall be borne
proportionately by Holders participating in a registration pursuant to this
Section 4(e)) shall be borne by the Company, including the reasonable fees and
expenses of a single special counsel for the holders of the Series E Preferred
Stock (which shall be borne by the Company).

            (f) Obligations of the Company. Whenever required to effect the
registration of any Registrable Securities under this Agreement, the Company
shall, as expeditiously as reasonably possible, in accordance with the intended
method of disposition thereof:

                  (i) Prepare and file with the Commission a registration
statement with respect to such Registrable Securities and use its best efforts
to cause such registration statement to become and remain effective.

                  (ii) Prepare and file with the Commission such amendments and
supplements to such registration statement and the prospectus used in connection
with such registration statement as may be necessary to comply with the
provisions of the Securities Act with respect to the disposition of all
securities covered by such registration statement and to keep such registration
statement effective, in the case of a firm commitment underwriting, until each
underwriter has completed the distribution of all securities purchased by it
and, in the case of any other offering, until the earlier of the sale of all
Registrable Securities covered thereby or one hundred eighty (180) days after
the effective date thereof; provided, however, that such 180-day period shall be
extended for a period of time equal to the period the Holder refrains from
selling any Registrable Securities included in such registration at the request
of an underwriter of the Common Stock or if the Company has provided the notice
described in subparagraph (vii) below.

                  (iii) Furnish to the Holders such number of copies of a
prospectus, including a preliminary prospectus, in conformity with the
requirements of the Securities Act, and such other documents as they may
reasonably request in order to facilitate the disposition of the Registrable
Securities owned by them that are included in such registration.

                  (iv) Use its best efforts to register and qualify the
securities covered by such registration statement under such other securities or
blue sky laws of such jurisdictions as shall be reasonably requested by the
Holders, provided, that the Company shall not be required in connection
therewith or as a condition thereto to qualify to do business or to file a
general consent to service of process in any such states or jurisdictions.

                  (v) Use its best efforts to list the securities covered by
such registration statement with any securities exchange, if any, on which the
Common Stock of the Company is then listed.

                                       13
<PAGE>

                  (vi) In the event of any underwritten public offering, enter
into and perform its obligations under an underwriting agreement, in usual and
customary form, with the managing underwriter(s) of such offering. Each Holder
participating in such underwriting shall also enter into and perform its
obligations under such an agreement.

                  (vii) Notify each Holder of Registrable Securities and each
underwriter under such registration statement at any time when a prospectus
relating thereto is required to be delivered under the Securities Act of the
happening of any event as a result of which the prospectus included in such
registration statement, as then in effect, includes an untrue statement of a
material fact or omits to state a material fact required to be stated therein or
necessary to make the statements therein not misleading in the light of the
circumstances then existing.

            (g) Furnish Information. It shall be a condition precedent to the
obligations of the Company to take any action pursuant to Sections 4(d) and 4(e)
that the selling Holders shall furnish to the Company such information regarding
themselves, the Registrable Securities held by them, and the intended method of
disposition of such securities as shall be required to effect the registration
of their Registrable Securities.

            (h) Indemnification. In the event any Registrable Securities are
included in a registration statement under Sections 4(d) or 4(e):

                  (i) To the extent permitted by law, the Company shall
indemnify and hold harmless each Holder, the partners, officers and directors of
each Holder, any underwriter (as defined in the Securities Act) for such Holder
and each Person, if any, who controls such Holder or underwriter within the
meaning of the Securities Act or the Exchange Act, against any losses, claims,
damages, or liabilities (joint or several) to which they may become subject
under the Securities Act, the Exchange Act or other federal or state law,
insofar as such losses, claims, damages or liabilities (or actions in respect
thereof) arise out of or are based upon any of the following statements,
omissions or violations (singly or collectively, a "Violation"):

                        (1) any untrue statement or alleged untrue statement of
a material fact contained in such registration statement, including any
preliminary prospectus or final prospectus contained therein or any amendments
or supplements thereto,

                        (2) the omission or alleged omission to state therein a
material fact required to be stated therein, or necessary to make the statements
therein not misleading, or

                        (3) any violation or alleged violation by the Company of
the Securities Act, the Exchange Act, any federal or state securities law or any
rule or regulation promulgated under the Securities Act, the Exchange Act or any
federal or state securities law in connection with the offering covered by such
registration statement, and the Company shall reimburse each such Holder, or a
partner, officer or director, underwriter or controlling Person of such Holder
for any legal or other expenses reasonably incurred by them, as incurred, in
connection with investigating or defending any such loss, claim, damage,
liability or action; provided, however, that the indemnity agreement contained
in this Section 4(h) shall not apply to amounts paid in

                                       14
<PAGE>

settlement of any such loss, claim, damage, liability or action if such
settlement is effected without the consent of the Company (which consent shall
not be unreasonably withheld), nor shall the Company be liable in any case for
any such loss, claim, damage, liability or action to the extent that it arises
out of or is based upon a Violation which occurs in reliance upon and in
conformity with written information furnished expressly for use in connection
with such registration by such Holder, or a partner, officer, director,
underwriter or controlling Person of such Holder.

                  (ii) To the extent permitted by law, each selling Holder shall
indemnify and hold harmless the Company, each of its directors and officers who
have signed the registration statement, each Person, if any, who controls the
Company within the meaning of the Securities Act, any underwriter and any other
Holder selling securities under such registration statement or any of such other
Holder's partners, directors or officers or any Person who controls such Holder
within the meaning of the Securities Act or the Exchange Act, against any
losses, claims, damages or liabilities (joint or several) to which the Company
or any such director, officer, controlling Person, underwriter or other such
Holder, or a partner, director, officer or controlling Person of such other
Holder may become subject under the Securities Act, the Exchange Act or other
federal or state law, insofar as such losses, claims, damages or liabilities (or
actions in respect thereto) arise out of or are based upon any Violation, in
each case to the extent that such Violation occurs in reliance upon and in
conformity with written information furnished by such Holder expressly for use
in connection with such registration; and each such Holder shall reimburse any
legal or other expenses reasonably incurred by the Company or any such director,
officer, controlling Person, underwriter or other Holder, partner, officer,
director or controlling Person of such other Holder in connection with
investigating or defending any such loss, claim, damage, liability or action;
provided, however, that the indemnity agreement contained in this Section 4(h)
shall not apply to amounts paid in settlement of any such loss, claim, damage,
liability or action if such settlement is effected without the consent of the
Holder, which consent shall not be unreasonably withheld; provided further, that
in no event shall any indemnity under this Section 4(h) exceed the net proceeds
from the offering received by such Holder.

                  (iii) Promptly after receipt by an indemnified party under
this Section 4(h) of notice of the commencement of any action (including any
governmental action), such indemnified party shall, if a claim in respect
thereof is to be made against any indemnifying party under this Section 4(h),
deliver to the indemnifying party a written notice of the commencement thereof
and the indemnifying party shall have the right to participate in, and, to the
extent the indemnifying party so desires, jointly with any other indemnifying
party similarly noticed, to assume the defense thereof with counsel mutually
satisfactory to the parties; provided, however, that an indemnified party shall
have the right to retain its own counsel, with the fees and expenses to be paid
by the indemnifying party, if representation of such indemnified party by the
counsel retained by the indemnifying party would be inappropriate due to actual
or potential differing interests between such indemnified party and any other
party represented by such counsel in such proceeding. The failure to deliver
written notice to the indemnifying party within a reasonable time of the
commencement of any such action, if prejudicial to its ability to defend such
action, shall relieve such indemnifying party of any liability to the
indemnified party under this Section 4(h), but the omission so to deliver
written notice to the indemnifying party shall not relieve it of any liability
that it may have to any indemnified party otherwise than under this Section
4(h).

                                       15
<PAGE>

                  (iv) In order to provide for just and equitable contribution
to joint liability under the Securities Act in any case in which either (A) any
Holder exercising rights under this Agreement, or any controlling Person of any
such Holder, makes a claim for indemnification pursuant to this Section 4(h) but
it is judicially determined (by the entry of a final judgment or decree by a
court of competent jurisdiction and the expiration of time to appeal or the
denial of the last right of appeal) that such indemnification may not be
enforced in such case notwithstanding the fact that this Section 4(h) provides
for indemnification in such case, or (B) contribution under the Securities Act
may be required on the part of any such selling Holder or any such controlling
Person in circumstances for which indemnification is provided under this Section
4(h), then, and in each such case, the Company or such Holder shall contribute
to the aggregate losses, claims, damages or liabilities to which they may be
subject (after contribution from others) in such proportion so that such Holder
is responsible for the portion represented by the percentage that the public
offering price of its Registrable Securities offered by and sold under such
registration statement bears to the public offering price of all securities
offered by and sold under such registration statement, and the Company and other
selling Holders are responsible for the remaining portion; provided, however,
that no Person guilty of fraudulent misrepresentation (within the meaning of
Section 11(f) of the Securities Act) shall be entitled to contribution from any
Person who was not guilty of such fraudulent misrepresentation.

                  (v) The obligations of the Company and Holders under this
Section 4(h) shall survive the completion of any offering of Registrable
Securities in a registration statement, and the termination of this Agreement.

            (i) "Market Stand-Off" Agreement. Each Holder hereby agrees that it
shall not, to the extent requested by the Company and an underwriter of Common
Stock of the Company, sell or otherwise transfer or dispose of any Registrable
Securities (other than Registrable Securities being registered in such offering)
for up to that period of time following the effective-date of a registration
statement of the Company filed under the Securities Act as is requested by the
managing underwriter(s) of such offering, not to exceed 180 days; provided,
however, that all officers, directors and five percent (5%) or greater
stockholders of the Company then holding Common Stock of the Company shall enter
into similar agreements.

      In order to enforce the foregoing covenant, the Company may impose stop
transfer instructions with respect to the then remaining Registrable Securities
of each Holder (and the shares or securities of every other Person subject to
the foregoing restriction) until the end of such period.

            (j) Limitation on Subsequent Registration Rights. The Company shall
not enter into any agreement with any holder or prospective holder of any
securities of the Company that would grant such holder rights to the
registration of shares of the Company's capital stock on more favorable terms
than those granted to holders of Preferred Stock, without the consent of at
least a majority of the holders of the then outstanding Preferred Stock, voting
on an as-if converted basis.

            (k) Termination of Registration Rights. No Holder shall be entitled
to exercise any right provided for in this Section 4 after the earlier of (i)
seven (7) years following the consummation of a Qualified IPO, (ii) such time as
Rule 144 or another similar exemption under the

                                       16
<PAGE>

Securities Act is available for the sale of all of such Holder's shares during a
three-month period without registration, or (iii) upon termination of the
Agreement, as provided in Section 5.

      5. Duration of Agreement. Except for those provisions that, by their
terms, terminate sooner, all rights and obligations of each Stockholder and the
Company under this Agreement shall terminate, and have no further force and
effect, upon the earlier of (a) the transfer in accordance with this Agreement
of all Shares held by such Stockholder, (b) upon written consent of (i) the
Stockholders holding at least sixty-six and 67/100 percent (66.67%) of the
shares of Preferred Stock (or shares of Common Stock issued upon conversion
thereof) held by all Stockholders; and (ii) the Stockholders holding a majority
of the shares of Common Stock (other than those shares specified in subparagraph
(i) above), or (c) the consummation of a transaction or series of related
transactions deemed to be a liquidation, dissolution or winding up of the
Company pursuant to the Company's Restated Certificate of Incorporation, as such
Restated Certificate of Incorporation may be amended from time to time.

      6. Board of Directors. The Company shall provide that its Board of
Directors will be composed of seven (7) members and the Investors listed on
Schedule II of this Agreement shall have the right to nominate three (3)
European members as set forth in this Agreement; provided, however, that these
three members will have the qualifications set forth below and be reasonably
acceptable to the Company:

            (a) Two members will have senior management experience with major
multinational medical device companies or their equivalent; and

            (b) One member will have significant financial and banking
experience (which may include service as a chief financial officer of a public
company), with respect to effecting a public offering of the Company on a major
exchange.

            (c) If an Investor listed on Schedule II to this Agreement is not
represented on the Company's Board of Directors by the directors appointed
pursuant to this Section 6, the Company shall invite a representative of such
Investor at such Investor's expense to attend all meetings of its Board of
Directors in a nonvoting observer capacity and, in this respect, shall give such
representative timely copies of all notices, minutes, consents and other
material that it provides to its directors.

            (d) The provisions of this Section 6 shall terminate upon the
earlier of the consummation of a firm commitment underwritten public offering by
the Company of shares of its Common Stock in connection with which all of the
outstanding shares of Preferred Stock are converted into shares of Common Stock.

      7. Severability; Governing Law. If any provisions of this Agreement shall
be determined to be illegal and unenforceable by any court of law, the remaining
provisions shall be severable and enforceable in accordance with their terms.
This Agreement shall be governed by, and

                                       17
<PAGE>

construed in accordance with, the internal laws of the State of California
without regard to conflict of laws provisions.

      8. Benefits of Agreement. This Agreement shall be binding upon and inure
to the benefit of the parties and their respective successors and assigns, legal
representatives and heirs; provided, that, except as otherwise specifically
permitted pursuant to this Agreement, neither this Agreement nor any of the
rights, interests or obligations hereunder shall be assigned by any party hereto
without the prior written consent of the Company. This Agreement sets forth the
entire agreement and understanding among the parties as to the subject matter
hereof and merges and supersedes all prior discussions, agreements and
understandings of any and every nature among them.

      9. Notices. All notices, requests, consents and other communications
hereunder to any party shall be deemed to be sufficient if contained in a
written instrument delivered in person or duly sent by first class registered or
certified mail, return receipt requested, postage prepaid, or, if to an
international address, by nationally recognized express courier, addressed to
such party at the address set forth below or such other address as may hereafter
be designated in writing by the addressee to the addressor listing all parties:

            (a)   If to the Company:

                  Micrus Corporation
                  Attention: Chief Financial Officer
                  610 Palomar Avenue
                  Sunnyvale, CA 94085

                  with a copy to:

                  Heller Ehrman Venture Law Group
                  Attn:  Glen R. Van Ligten
                  2775 Sand Hill Road
                  Menlo Park, CA  94070

            (b)   If to J. Todd Derbin:

            (c)   If to Joseph A. Horton, M.D.:

                  80 Rutledge Avenue
                  Charleston, SC 29401-1725

                  If to the Investors, to the names and addresses set forth on
Schedule I, or to such address subsequently provided by an Investor to the
Company.

                                       18
<PAGE>

      All such notices, advises and communications shall be deemed to have been
received (a) in the case of personal delivery, on the date of such delivery and
(b) in the case of mailing, on the third day after the posting thereof.

      10. Changes. The terms and provisions of this Agreement may not be
modified or amended, or any of the provisions hereof waived, temporarily or
permanently, except pursuant to the written consent of (a) the Company, (b) the
Stockholders holding at least sixty-six and 67/100 percent (66.67%) of the
shares of Preferred Stock (or shares of Common Stock issued upon conversion
thereof) held by all Stockholders, and (c) the Stockholders holding a majority
of the shares of Common Stock (other than those shares specified in subparagraph
(b) of this Section 10) held by all Stockholders; provided however, that, any
modifications or amendments resulting from the addition of holders of a new
series or sub-series of preferred stock of this Company as parties to this
Agreement in connection with the sale and issuance of such new series or
sub-series of preferred stock by the Company shall not require the consent of
any Stockholders under this Agreement unless the holders of such new series or
sub-series of stock of this Company are granted, upon such modification or
amendment of this Agreement, terms or rights in preference or in addition to the
terms or rights held by the then-existing Stockholders. Upon approval of
modifications or amendments by the requisite percentages of the Stockholders
hereunder, the Company shall not be required to independently give its consent.

      11. Captions. The captions herein are inserted for convenience only and
shall not define, limit, extend or describe the scope of this Agreement or
affect the construction hereof.

      12. Nouns and Pronouns. Whenever the context may require, any pronouns
used herein shall include the corresponding masculine, feminine or neuter forms
and the singular form of names and pronouns shall include the plural and
vice-versa.

      13. Merger Provision; Termination of Previous Stockholders' Agreement.
This Agreement (as the same may be amended from time to time) and the Purchase
Agreement constitute the entire agreement among the parties pertaining to the
subject matter hereof and supersede all prior and contemporaneous agreements
therewith, including without limitation, the Previous Stockholders' Agreement,
which is hereby terminated and no longer of any force or effect.

      14. Counterparts. This Agreement may be executed in one or more
counterparts and by facsimile, each of which shall be deemed to be an original,
but all of which taken together shall constitute one and the same instrument.

      15. Covenants of the Company. The Company hereby covenants as set forth in
the following subsections with each Investor as follows:

            (a) Books and Records. The Company shall keep and maintain adequate
and proper books and records of account, in which complete entries are made in
accordance with generally accepted accounting principles consistently applied
and in accordance with all applicable laws, rules and regulations, reflecting
all financial and other transactions of the Company normally

                                       19
<PAGE>

or customarily included in books and records of account of companies engaged in
the same or similar businesses and activities as the Company.

            (b) Financial and Business Information. The Company shall furnish to
each Major Investor:

                  (i) as soon as available and in any event within 90 days after
the end of each fiscal year of the Company, a copy of the audited balance sheet
of the Company as of the end of such fiscal year and the related audited
statements of income, stockholders' equity, and changes in financial condition
for such fiscal year, all prepared in reasonable detail, and certified by
independent certified public accountants of recognized national standing as
presenting fairly the financial position of the Company and approved by the
Board of Directors of the Company, including footnotes and setting forth in
comparative form the corresponding figures for the corresponding period of the
preceding fiscal year;

                  (ii) as soon as available and in any event within 45 days
after the end of each fiscal quarter of the Company (other than the last quarter
of each fiscal year) a copy of the unaudited balance sheet of the Company as of
the end of such quarter and the related unaudited statements of income,
stockholders' equity, and changes in financial condition of the Company for the
periods commencing at the end of the previous quarter and ending at the end of
such quarter and commencing at the beginning of the fiscal year and ending at
the end of such quarter, in each case including footnotes and setting forth in
comparative form the corresponding figures for the corresponding period of the
preceding fiscal year;

                  (iii) as soon as available and in any event within 30 days
prior to the commencement of each fiscal year of the Company, an annual budget
and operating plan for the Company; and

                  (iv) copies of all additional information and reports provided
to the holders of any class of the Company's securities.

            (c) Inspection. The Company shall permit each Major Investor at such
Major Investor's expense, to visit and inspect the Company's properties, to
examine its books of account and records and to discuss the Company's affairs,
finances and accounts with its officers, all at such reasonable times as may be
reasonably requested by the Major Investor; provided, however, that the Company
shall not be obligated pursuant to this Section 15 to provide access to any
information that it reasonably considers to be a trade secret or similar
confidential information.

            (e) Termination. The provisions of this Section 15 shall terminate
upon the earlier of the consummation of a firm commitment underwritten public
offering by the Company of shares of its Common Stock in connection with which
all of the outstanding shares of Preferred Stock are converted into shares of
Common Stock or when the Company first becomes subject to the periodic reporting
requirements of Sections 13 or 15(d) of the Exchange Act.

                            [SIGNATURE PAGES FOLLOW]

                                       20
<PAGE>

      The parties hereto have executed this Micrus Corporation Amended and
Restated Stockholders' Agreement as of the date first written above.

                                           THE CORPORATION:

                                           MICRUS CORPORATION

                                           /s/ Robert A. Stern
                                           -------------------------------------
                                           Signature

                                           Robert A. Stern,
                                           Executive Vice President
                                           -------------------------------------
                                           Print Name and Title of Signatory

                                           FOUNDERS:

                                           _____________________________________
                                           J. Todd Derbin

                                           _____________________________________
                                           Joseph A. Horton, M.D.

<PAGE>

      The parties hereto have executed this Micrus Corporation Amended and
Restated Stockholders' Agreement as of the date first written above.

                                  INVESTOR:

                                  _____________________________________
                                  Signature

                                  _____________________________________
                                  Print Name of Investor

                                  _____________________________________
                                  Print name and title of signatory (if entity)

<PAGE>

                                   SCHEDULE 1

                                    INVESTORS

            Investors                                Addresses

Adjuvant Foundation (f.k.a. Irving        c/o Patricia Lanigan - Fund
Harris Foundation B)                      Administrator
                                          2 North LaSalle Street
                                          Suite 400
                                          Chicago, IL 60602

Gary and Debra Anderson (JTWROS)          1750 Camino Manadero
                                          Santa Barbara, CA 93111

Aventic AG                                c/o Mr. Markus Oswald
                                          Giesshubelstraussa 4
                                          Zurich, Postfach, 8027
                                          Switzerland

Barbara Azar and Paul Azar                516 Landry Street
                                          Lafayette, LA 70506-4626

Andrew Bazos                              188 Northrop Street
                                          Bridgewater, CT 06752-1608

Stephen C. Berens M.D. and Roberta J.     16384 Tudor Drive
Berens                                    Encino, CA 94136-4165

Thomas V. Bertuccini, M.D.                216 Kings Rd.
                                          Lafayette, LA 70506

Franklin D. Brown                         10173 E. Horizon Drive
                                          Scottsdale, AZ 85262

Maurice Buchbinder                        Attn: Sharp Memorial Hospital
                                          9834 Genesee Ave., #310
                                          La Jolla, CA 92037

Pete E. Campanella                        11 Blades Run Drive
                                          Shrewsbury, NJ 07702

Louis A. Cannon, M.D.                     25 Hunters Ridge
                                          Saginaw, MI 48603

Cardiva S.L.                              c/o Ignacio Vega
                                          48073 Bilbao
                                          Vizcaya,
                                          Spain

<PAGE>

            Investors                                Addresses

Della L. Cass and Timothy R. Cass, as     c/o Dean Witter
trustee under the Cass Family Living      1400 Del Monte Center
Trust Agreement                           Monterey, CA 93940

Christopher U. Cates, M.D.                315 Riverhall Court
                                          Atlanta, GA 30350

Cathex Co., Ltd.                          Yoyogi NT Bldg. 2-28-7
                                          Yoyogi Shibuya-ku
                                          Tokyo 00151
                                          Japan

Bert E. Coates                            1021 5th Street West
                                          Kirkland, VA 98033

Victor E. Corrigan                        5655 Peachtree Dunwoody Rd.
                                          Atlanta, GA 30343

Couderay Partners                         c/o Patricia Lanigan - Fund
                                          Administrator
                                          2 North LaSalle Street
                                          Suite 400
                                          Chicago, IL 60602

Don Crawford                              1021 5th Street West
                                          Kirkland, VA 98033

E. John deBeer                            5 Harvard Street
                                          Marblehead, MA 01945

Delaware Charter Guarantee &
Trust TTEE FBO Michael Stillabower
IRA

James L. DellaGatta                       28595 Rancho Del Sol
                                          Laguna Niguel, CA 92677

Marc A. DiGeronimo                        196 Whalon Street
                                          Fitchburg, MA 01420

International Life Science Partners       Centennial Towers, Suite 305
                                          2454 West Bay Road
                                          Grand Cayman, Cayman Islands
                                          Attn: Jean-marc Lesieru

Justin Duckworth                          15 Ringmer Avenue, Fulham, London,
                                          U.K. SW6 SLP

Frank Feist                               Stein Str. 9
                                          Munich, Germany

<PAGE>

            Investors                                Addresses

Arnoldo Fiedotin                          1818 W. Wesley Rd. NW
                                          Atlanta, GA 30327

Ellen Flamm                               1158 5th Avenue, #9
                                          New York, NY 10029

Frank Walker and Claire Walker            260 Cayney Lane, Apt. 211
                                          Newport Beach, CA 92663-1613

Nick Fravala                              4255 Plateau Road
                                          Reno, NV 89509

Getz Bros. Co., Ltd.                      Sumitome Seimei Aoyama
                                          Bldg. 3-1-30 Minami-Aoyama
                                          Minato-ku Tokyo
                                          107-0062
                                          Japan
                                          Attention:  Paul Bond

Global Capital Advisors GMBH              c/o Mr. Eric Achtmann
                                          Franevsettc 28
                                          D-80469
                                          Munich, Germany

Global Venture Advisors GMBH              Jarrholzweg 1 D-82284
                                          Grafrath, Germany
                                          422 Catharine Street
David D. Goltra, Sr. and Phyllis Goltra   Philadelphia, PA 19147

William J. Gore                           13310 Foxmoor Trail
                                          Cleveland, OH 44026

Clyde C. Greco                            P.O. Box 11427
                                          Santa Rosa, CA 95406

Clyde C. Greco, Jr.                       c/o Law Offices of Greco & Traficante
                                          350 West Ash St., Suite 850
                                          San Diego, CA  92101

Daniel Julian Green                       5 Kingstown Street, London, NWI  8JP
                                          UK

Frank G. Groenewegen                      c/o Cardiologic GmbH
                                          Rotwandweg 5A
                                          82024 Taaufkirchen
                                          82024
                                          Germany

<PAGE>

            Investors                                Addresses

Dr. Max Guntersdorfer                     Melakstr. AZ
                                          Goafing 85567
                                          Germany

Harris Venture Partners LLC               c/o Patricia Lanigan - Fund
                                          Administrator
                                          2 North LaSalle St., Suite 400
                                          Chicago, IL 60602

Health Reform Technology, L.P.            Attn:  Lloyds Bank PLC
                                          1 Legg Street
                                          Chelmsford Essex
                                          United Kingdom

Michael R. Henson                         2 Via Presea
                                          Coto de Caza, CA 92679

Michael R. Henson, TTEE Henson Family     2 Via Presea
Trust, 1/8/87                             Coto de Caza, CA 92679
                                          Attention: Henson Family Trust,
                                          1/8/97

Robert Hilekes                            c/o Dennis Doss
                                          Doss & Page
                                          Suite 210
                                          1920 Main Street
                                          Irvine, CA  92614-7223

Fred Holubow                              c/o Harris Aortic Partners
                                          2 North La Salle, Suite 400
                                          Chicago, IL 60602

Irving B. Harris, TTEE of the Irving B.   c/o Patricia Lanigan - Fund
Harris Revocable Trust                    Administrator
                                          2 North LaSalle Street
                                          Suite 400
                                          Chicago, IL 60602

Irving Harris Foundation                  c/o Patricia Lanigan - Fund
                                          Administrator
                                          2 North LaSalle Street
                                          Suite 400
                                          Chicago, IL 60602

Jack R. Polsky, TTEE of the Jack Polsky   c/o Patricia Lanigan - Fund
Investment Trust                          Administrator
                                          2 North LaSalle Street
                                          Suite 400
                                          Chicago, IL 60602

<PAGE>

            Investors                              Addresses

JAIC - Henson MedFocus Fund, LLC

Pierre Hochuli                            Av. Beassive 72 B-1640
                                          Rhode St.
                                          Geneva, Switzerland

Donald E. Jansen, M.D.                    35 Sherington Place
                                          Atlanta, GA 30350

Christopher A. Jasin                      4303 Talmadge Road #201
                                          Toledo, OH 43623

Jerome Kahn Jr., TTEE of the Jerome       c/o Patricia Lanigan - Fund
Kahn, Jr. Revocable Trust                 Administrator
                                          2 North LaSalle Street
                                          Suite 400
                                          Chicago, IL 60602

Paul K. Joas                              c/o Dain Bosworth, Inc.
                                          P.O. Box 1160
                                          Minneapolis, MN 55440

Graeme Johnson                            Flat 6 4 Audley Square
                                          London, United Kingdom

Margot Kahn                               c/o Patricia Lanigan - Fund
                                          Administrator
                                          2 North LaSalle Street
                                          Suite 400
                                          Chicago, IL 60602

Martin Kallen                             1 Woburn House,
                                          Whinghill Court
                                          Cross Road, Ascot
                                          Berks SL5 9RU
                                          United Kingdom

Harriet R. Karesh

Richard B. Kasdan, M.D.                   541 Linden Lane
                                          Pittsburgh, PA 15208

Jack Bing Wah Ken and Betty Ken Trust     1345 Brandt Road
(DTD 5/04/89)                             Hillsborough, CA 94010

<PAGE>

            Investors                                Addresses

William D. Knopf                          5665 Peachtree Dunwoody Rd.
5665 Peachtree Dunwoody Rd.               Atlanta, GA 30342
Atlanta, GA 30342                         Attention: Atlanta Cardiology Group

Kroll Family Trust                        c/o Stephen Kroll
3591 Courtside Circle                     3591 Courtside Circle
Huntington Beach, CA 92649                Huntington Beach, CA 92649

Andre Kuch                                Pognerstrasse 25
                                          8A379
                                          Munich, Germany

James Ladner                              Gartenstrasse 10
                                          Zurich, Switzerland CH 8002
                                          Attention: RP & C Intl. - Zurich
                                          Representative Office

Nicholas J. Lembo                         900 Oakdale Road
                                          Atlanta, GA 30307

Craig A. Lillibridge                      5352 Jackman Road
                                          Toledo, OH 43613

Lincoln Trust Co. Custodian
FBO Gareld W. Anderson, IRA

Lincoln Trust Company, Custodian
FBO S.Richard Denardo, IRA

William J. Livingston                     1400 Santiago Drive
                                          Newport Beach, CA 92660

Lushan Venture Consult GMBH               Oberfeldallee 8
                                          Ginnwald D-82031
                                          Germany

<PAGE>

            Investors                                Addresses

Mach Capital L.P.                         EFG Reads Trust Co. Limited
                                          Att. Jonathan Buesnel
                                          No. 1 Seaton Place
                                          PO Box 641
                                          St. Helier, Jersey JE4 8YJ
                                          Channel Islands
                                          U.K.

Mach II Limited Partnership               EFG Reads Trust Co. Limited
                                          Att. Jonathan Buesnel
                                          No. 1 Seaton Place
                                          PO Box 641
                                          St. Helier, Jersey JE4 8YJ
                                          Channel Islands
                                          U.K.

Peter Martin                              c/o Patricia Lanigan - Fund
                                          Administrator
                                          2 North LaSalle Street
                                          Suite 400
                                          Chicago, IL 60602

Paul McCormick                            28482 Rancho Grande
                                          Laguna Niguel, CA 92677

W. Gary McCord Jr.                        9163 Cedar Ridge Drive
                                          Granite Bay, CA 95746

Peter Melhado                             530 Fifth Avenue, 25th Floor
                                          New York, NY 10036

Michigan Cardiology Investments, LLC

MicroValue AG                             c/o Mr. Goran Lukic
                                          Muhlebachstrasse 54
                                          Zurich, Switzerland 8008

Mitchell Dann TTEE M. Dann & Co., Inc.    4020 W. Lake Creek Drive
Profit Sharing Plan                       Jackson, WY 83001

Laura and Ken Morse                       36 Commonwealth Avenue
                                          Boston, MA 02116-3104

HBM BioVentures (Cayman) Ltd.             Centennial Towers, Suite 305
                                          2454 West Bay Road
                                          Grand Cayman, Cayman Islands
                                          Attn: Jean-marc Lesieru

<PAGE>

            Investors                                Addresses

Jeffrey O'Donnell                         126 Rossmore Drive
                                          Malvern, PA 19355

Gunnar M. Pah                             c/o CARDIOMED
                                          Raiffeisenallee 6
                                          82041 Deisenhofen

Paine Webber FBO David H. Talbot
Rollover IRA

James W. Paul                             2512 Via Sanchez
                                          Palos Verdes Estates, CA 90274

Jill T. Pearson                           27812 Ruisenor
                                          Mission Viejo, CA 92692

David E. Pejsa                            8529 Elkrun Drive
                                          Clarkston, MI 48348

James J. Pelts                            c/o Patricia Lanigan - Fund
                                          Administrator
                                          2 North LaSalle Street
                                          Suite 400
                                          Chicago, IL 60602

Polaris Partners, L.P.                    530 Fifth Avenue, 25th Floor
                                          New York, NY 10036
                                          Attention: Mr. Peter Melhado

Polytechnos Medical Devices Ltd.          P.O. Box 431 13-15
                                          Victoria Road St. Peter Port
                                          Guernsey, Channel Islands
                                          United Kingdom GY1 3ZD
                                          Attention:  Mr. Peter I. Gillson

Matthew Powers                            c/o Weil Gotshal & Manges LLP
                                          201 Redwood Shores Parkway
                                          Redwood Shores, CA 94065

Ronald Lee Rahal                          3433 Darlington
                                          Toledo, OH 43606

Noel Rahn                                 225 South Sixth Street
                                          Suite 3355
                                          Minneapolis, MN 55402
                                          333 South Hope Street

Philip Reimann                            Kuglmullerstr. 78
                                          Muenchen, Germany 80638

<PAGE>

            Investors                                Addresses

Michael Resnick                           c/o Patricia Lanigan - Fund
                                          Administrator
                                          2 North LaSalle Street
                                          Suite 400
                                          Chicago, IL 60602

Resolute Partners                         106 Vine Avenue
                                          Highland Park, IL 60035

Gregory P. Riehle                         58 Widewater
                                          Hilton Head, SC 29926

Rotonda Foundation (f.k.a. Irving         c/o Patricia Lanigan - Fund
Harris Foundation A)                      Administrator
                                          2 North LaSalle Street
                                          Suite 400
                                          Chicago, IL 60602

Roxanne H. Frank Trust                    c/o Patricia Lanigan - Fund
                                          Administrator
                                          2 North LaSalle Street
                                          Suite 400
                                          Chicago, IL 60602

Kenneth Rusk                              2360 Gradwohl
                                          Toledo, OH 43617

Charles Sallah                            4303 Talmadge Road #201
                                          Toledo, OH 43623

Dr. Christian Schneider                   Lerchenweg 6
                                          Eching lammersee
                                          Munich, Germany 82279

Dr. Anton E. Schrafl                      Talstrasse 83
                                          Zurich, Switzerland 8001

Tammy L. Shemak                           1236 East Meadow Drive
                                          Oregon, OH 43616

Hirohisa Shinzaki                         2-14-1 Hijirgaoka Tama City
                                          Tokyo, Japan

Stuart L. Silverman, M.D.                 314 Schenley Road
                                          Pittsburgh, PA 15213

John F. Somers                            111 North Drive
                                          Amherst, NY 14226

<PAGE>

            Investors                                Addresses

Gregg W. Stone                            21 Wyckham Hill Lane
                                          Greenwich, CT 06831-3049

Steven Strausbaugh                        7367 Kings Park
                                          Toledo, OH 43617

Gregory D. Sullivan                       122 Liberty Bell Circle
                                          Weymouth, MA 02189-2154

Swartz Family Limited Partnership #4      c/o Andrew Schenker
                                          40 Marguette Drive
                                          Smithtown, NY 11787

John B. Talbot, M.D.                      1186 Beechwood Court
                                          Pittsburgh, PA 15206

Jeffrey Thiel                             8 Thornapple
                                          Laguna Niguel, CA 92677

Marc Tilman                               Vossenbergstraat 39
                                          Hasselt
                                          B-3500

Stuart J. Toporoff, M.D.                  5665 Peachtree Dunwoody
                                          Atlanta, GA 30342
                                          Attention: Atlanta Cardiology Group

Virginia H. Polsky Trust                  c/o Patricia Lanigan - Fund
                                          Administrator
                                          2 North LaSalle Street
                                          Suite 400
                                          Chicago, IL 60602

Gerard von Hoffman                        3 Via Presea
                                          Coto de Caza, CA 92679

Warren G. McCord TTEE, Warren G. McCord   4 Aikahi Loop
Rev. Lvg. Tr. UA dated 4/6/84             Kailua, HI 96734
                                          Attention: W. G. McCord Revocable
                                          Living Trust dated 4/6/84

Branco Weiss                              Hallwystrasse 71
                                          Zurich, Switzerland CH-8036
                                          Attention: Sekretariat

Gary N. Wilner                            2349 Wood Path Lane
                                          Highland Park, IL 60035-2045

Steven J. Yakubov                         2234 Onandaga Drive
                                          Columbus, OH 43221

David R. Young                            604 St. James Place
                                          Newport Beach, CA 92663

<PAGE>

                                   SCHEDULE II

                                 Major Investors

                           aventic AG

                           Cathex Co.

                           International Life Science
                           Partners

                           Getz Bros. Co., Ltd.

                           Michael Henson

                           Healthforum Opportunities

                           Irving B. Harris, TTEE of the
                           Irving B. Harris Revocable
                           Trust

                           MicroValue AG

                           MVI Medical Venture

                           William Livingston

                           Polytechnos Medical Devices

                           Robin Hood NV

                           Branco Weiss

                    Investors with Nominee/Observation Rights

                          HBM BioVentures (Cayman) Ltd.

                                   Aventic AG

                           DrKB Life Science Partners

                           (Kleinwort Benson Limited)

                                  MicroValue AG

                           Polytechnos Medical Devices
                                      Ltd.