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                                                                    Exhibit 4.2

                       INTRABIOTICS PHARMACEUTICALS, INC.

                 AMENDED AND RESTATED INVESTORS RIGHTS AGREEMENT

                                OCTOBER 15, 1999

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                                TABLE OF CONTENTS
                                -----------------

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1.       REGISTRATION RIGHTS......................................................................................1

         1.1      Definitions.....................................................................................1

         1.2      Request for Registration........................................................................2

         1.3      Company Registration............................................................................4

         1.4      Obligations of the Company......................................................................4

         1.5      Furnish Information.............................................................................5

         1.6      Expenses of Demand Registration.................................................................6

         1.7      Expenses of Company Registration................................................................6

         1.8      Underwriting Requirements.......................................................................6

         1.9      Delay of Registration...........................................................................7

         1.10     Indemnification.................................................................................7

         1.11     Reports under Securities Exchange Act of 1934...................................................9

         1.12     Form S-3 Registration...........................................................................9

         1.13     Assignment of Registration Rights..............................................................10

         1.14     Limitations on Subsequent Registration Rights..................................................10

         1.15     "Market Stand-Off" Agreement...................................................................11

         1.16     Termination of Registration Rights.............................................................11

2.       COVENANTS OF THE COMPANY................................................................................12

         2.1      Delivery of Financial Statements...............................................................12

         2.2      Inspection.....................................................................................13

         2.3      Right of First Offer...........................................................................13

         2.4      IRC Section 305................................................................................14

         2.5      Key-Person Insurance...........................................................................14

         2.6      Confidentiality Agreements.....................................................................15

         2.7      Announcements..................................................................................15

         2.8      Transactions With Affiliates...................................................................15

         2.9      Issuance of Series H Preferred Stock...........................................................15

         2.10     Termination Of Covenants.......................................................................15

3.       MISCELLANEOUS...........................................................................................15

         3.1      Successors and Assigns.........................................................................15

         3.2      Governing Law..................................................................................16

         3.3      Counterparts...................................................................................16


                                       i

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         3.4      Titles and Subtitles...........................................................................16

         3.5      Notices........................................................................................16

         3.6      Expenses.......................................................................................16

         3.7      Amendments and Waivers.........................................................................16

         3.8      Severability...................................................................................16

         3.9      Aggregation of Stock...........................................................................16

         3.10     Entire Agreement...............................................................................16
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                                       ii

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                       INTRABIOTICS PHARMACEUTICALS, INC.
                 AMENDED AND RESTATED INVESTORS RIGHTS AGREEMENT

              This AMENDED AND RESTATED INVESTORS RIGHTS AGREEMENT (this
"Agreement") is made as of the 15th day of October, 1999, by and between
INTRABIOTICS PHARMACEUTICALS, INC., a Delaware corporation (the "Company"), and
the investors listed on Schedule A hereto, each of which is herein referred to
as an "Investor."

                                    RECITALS

              WHEREAS, the Company and certain of the Investors ("New
Investors") are parties to the Series H Preferred Stock and Warrant Purchase
Agreement of even date herewith (the "Stock Purchase Agreement"); and

              WHEREAS, the Company and the remaining Investors (the "Existing
Investors") are parties to the existing Amended and Restated Investors' Rights
Agreement dated as of November 24, 1998, as amended (the "Existing Agreement");
and

              WHEREAS, in order to induce further investment in the Company
pursuant to the Stock Purchase Agreement, the Existing Investors and the Company
hereby agree that this Agreement shall amend and restate the Existing Agreement
and shall govern the rights of the Investors to cause the Company to register
shares of Common Stock issuable to the Investors and certain other matters as
set forth herein;

                                    AGREEMENT

              NOW, THEREFORE, in consideration of the mutual agreements,
covenants, and conditions set forth herein, the Company and each of the
Investors hereby agree that effective upon the closing of the issuance and sale
of Series H Preferred Stock to the New Investors pursuant to the Stock Purchase
Agreement, all of the provisions of the Existing Agreement shall be null and
void and superseded by the rights and obligations set forth in this Agreement,
and further agree as follows:

1.       REGISTRATION RIGHTS.  The Company covenants and agrees as follows:

         1.1      DEFINITIONS. For purposes of this Agreement:

                         (a)    The term "Act" means the Securities Act of 1933,
 as amended.

                         (b)    The term "Form S-3" means such form under the
Act as in effect on the date hereof or any registration form under the Act
subsequently adopted by the SEC which permits inclusion or incorporation of
substantial information by reference to other documents filed by the Company
with the SEC.

                         (c)    The term "Holder" means any person owning or
having the right to acquire Registrable Securities or any assignee thereof in
accordance with Section 1.13 hereof.

                         (d)    The term "1934 Act" shall mean the Securities
Exchange Act of 1934, as amended.


                                       1.

<PAGE>

                         (e)    The term "register," "registered," and
"registration" refer to a registration effected by preparing and filing a
registration statement or similar document in compliance with the Act, and the
declaration or ordering of effectiveness of such registration statement or
document.

                         (f)    The term "Registrable Securities" means (i) the
Common Stock of the Company issuable or issued upon conversion of the Series A
Preferred Stock, Series B Preferred Stock, Series C Preferred Stock, Series D
Preferred Stock, Series E Preferred Stock, Series F Preferred Stock, Series G
Preferred Stock of the Company and Series H Preferred Stock and (ii) any 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 the shares
referenced in (i) and (ii) above, excluding in all cases, however, any
Registrable Securities sold by a person in a transaction in which such person's
rights under this Section 1 are not assigned.

                         (g)    The number of shares of "Registrable Securities
then outstanding" shall be determined by the number of shares of Common Stock
outstanding which are, and the number of shares of Common Stock issuable
pursuant to then exercisable or convertible securities which are, Registrable
Securities.

                         (h)    The term "SEC" shall mean the Securities and
Exchange Commission.

         1.2      REQUEST FOR REGISTRATION.

                         (a)    If the Company shall receive at any time after
the earlier of (i) December 31, 2000, or (ii) six (6) months after the effective
date of the first registration statement for a public offering of securities of
the Company (other than a registration statement relating either to the sale of
securities to employees of the Company pursuant to a stock option, stock
purchase or similar plan or a SEC Rule 145 transaction), a written request from
the Holders of a majority of the Registrable Securities then outstanding that
the Company file a registration statement under the Act, the gross proceeds of
which would exceed $3,000,000, then the Company shall:

                                (i)      within ten (10) days of the receipt
thereof, give written notice of such request to all Holders; and

                                (ii)     effect as soon as practicable, and in
any event within sixty (60) days of the receipt of such request, the
registration under the Act of all Registrable Securities which the Holders
request to be registered, subject to the limitations of subsection 1.2(b),
within twenty (20) days of the mailing of such notice by the Company in
accordance with Section 3.5.

                         (b)    If the Holders initiating the registration
request hereunder ("Initiating Holders") intend to distribute the Registrable
Securities covered by their request by means of an underwriting, they shall so
advise the Company as a part of their request made pursuant to subsection 1.2(a)
and the Company shall include such information in the written notice referred to
in subsection 1.2(a). The underwriter will be selected by the Company and


                                       2.

<PAGE>

shall be reasonably acceptable to a majority in interest of the Initiating
Holders. In such event, the right of any Holder to include such Holder's
Registrable Securities in such registration shall be conditioned upon such
Holder's participation in such underwriting and the inclusion of such Holder's
Registrable Securities in the underwriting (unless otherwise mutually agreed by
a majority in interest of the Initiating Holders and such Holder) to the extent
provided herein. All Holders proposing to distribute their securities through
such underwriting shall (together with the Company as provided in subsection
1.4(e)) enter into an underwriting agreement in customary form with the
underwriter or underwriters selected for such underwriting. Notwithstanding any
other provision of this Section 1.2, if the underwriter advises the Initiating
Holders in writing that marketing factors require a limitation of the number of
shares to be underwritten, then the Initiating Holders shall so advise all
Holders of Registrable Securities which would otherwise be underwritten pursuant
hereto, and the number of shares of Registrable Securities that may be included
in the underwriting shall be allocated among all Holders thereof, including the
Initiating Holders, in proportion (as nearly as practicable) to the amount of
Registrable Securities of the Company owned by each Holder; provided, however,
that the number of shares of Registrable Securities to be included in such
underwriting shall not be reduced unless all other securities are first entirely
excluded from the underwriting.

                         (c)    Notwithstanding the foregoing, if the Company
shall furnish to Holders requesting a registration pursuant to this Section 1.2,
a certificate signed by the Chief Executive Officer of the Company stating that
in the good faith judgment of the Board of Directors of the Company, it would be
seriously detrimental to the Company and its stockholders for such registration
statement to be filed and it is therefore essential to defer the filing of such
registration statement, the Company shall have the right to defer taking action
with respect to such filing for a period of not more than one hundred twenty
(120) days after receipt of the request of the Initiating Holders; provided,
however, that the Company may not utilize this right more than once in any
twelve-month period.

                         (d)    In addition, the Company shall not be obligated
to effect, or take any action to effect, any registration pursuant to this
Section 1.2:

                                (i)      after the Company has effected two
registrations pursuant to this Section 1.2 and such registrations have been
declared or ordered effective:

                                (ii)     if within thirty (30) days of receipt
of a written request from Initiating Holders pursuant to Section 1.2(a), the
Company gives notice to the Holders of the Company's intention to make its first
registered public offering within ninety (90) days;

                                (iii)    during the period starting with the
date of filing of, and ending on a date one hundred eighty (180) days after the
effective date of, a registration subject to Section 1.3 hereof; provided that
the Company is actively employing in good faith all reasonable efforts to cause
such registration statement to become effective; or

                                (iv)     if the Initiating Holders propose to
dispose of shares of Registrable Securities that may be immediately registered
on Form S-3 pursuant to a request made pursuant to Section 1.12 below.


                                       3.

<PAGE>

         1.3      COMPANY REGISTRATION. If (but without any obligation to do so)
the Company proposes to register (including for this purpose a registration
effected by the Company for stockholders other than the Holders) any of its
stock or other securities under the Act in connection with the public offering
of such securities solely for cash (other than the Company's first registered
public offering of its securities, a registration relating solely to the sale of
securities to participants in a Company stock plan, a registration on any form
which does not include substantially the same information as would be required
to be included in a registration statement covering the sale of the Registrable
Securities or a registration in which the only Common Stock being registered is
Common Stock issuable upon conversion of debt securities which are also being
registered), the Company shall, at such time, promptly give each Holder written
notice of such registration. Upon the written request of each Holder given
within twenty (20) days after mailing of such notice by the Company in
accordance with Section 3.5, the Company shall, subject to the provisions of
Section 1.8, cause to be registered under the Act all of the Registrable
Securities that each such Holder has requested to be registered.

         1.4      OBLIGATIONS OF THE COMPANY. Whenever required under this
Section 1 to effect the registration of any Registrable Securities, the Company
shall, as expeditiously as reasonably possible:

                         (a)    Prepare and file with the SEC a registration
statement with respect to such Registrable Securities and use its best efforts
to cause such registration statement to become effective, and, upon the request
of the Holders of a majority of the Registrable Securities registered
thereunder, keep such registration statement effective for a period of up to one
hundred twenty (120) days or until the distribution contemplated in the
registration statement has been completed; provided, however, that (i) such
120-day period shall be extended for a period of time equal to the period the
Holder refrains from selling any securities included in such registration at the
request of an underwriter of Common Stock (or other securities) of the Company;
and (ii) in the case of any registration of Registrable Securities on Form S-3
which are intended to be offered on a continuous or delayed basis, such 120-day
period shall be extended, if necessary, to keep the registration statement
effective until all such Registrable Securities are sold, provided that Rule
415, or any successor rule under the Act, permits an offering on a continuous or
delayed basis, and provided further that applicable rules under the Act
governing the obligation to file a post-effective amendment permit, in lieu of
filing a post-effective amendment which (I) includes any prospectus required by
Section 10(a)(3) of the Act or (II) reflects facts or events representing a
material of fundamental change in the information set forth in the registration
statement, the incorporation by reference of information required to be included
in (I) and (II) above to be contained in periodic reports filed pursuant to
Section 13 or 15(d) of the 1934 Act in the registration statement.

                         (b)    Prepare and file with the SEC 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 Act with respect to the disposition of all securities
covered by such registration statement.

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


                                       4.

<PAGE>

                         (d)    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, unless the Company is
already subject to service in such jurisdiction and except as may be required by
the Act.

                         (e)    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 of such
offering. Each Holder participating in such underwriting shall also enter into
and perform its obligations under such an agreement.

                         (f)    Notify each Holder of Registrable Securities
covered by such registration statement at any time when a prospectus relating
thereto is required to be delivered under the 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)    Cause all such Registrable Securities registered
pursuant hereto to be listed on each securities exchange on which similar
securities issued by the Company are then listed.

                         (h)    Provide a transfer agent and registrar for all
Registrable Securities registered pursuant hereto and a CUSIP number for all
such Registrable Securities, in each case not later than the effective date of
such registration.

                         (i)    Furnish, at the request of any Holder requesting
registration of Registrable Securities pursuant to this Section 1, on the date
that such Registrable Securities are delivered to the underwriters for sale in
connection with a registration pursuant to this Section 1, if such securities
are being sold through underwriters, or, if such securities are not being sold
through underwriters, on the date that the registration statement with respect
to such securities becomes effective, (i) an opinion, dated such date, of the
counsel representing the Company for the purposes of such registration, in form
and substance as is customarily given to underwriters in an underwritten public
offering, addressed to the underwriters, if any, and to the Holders requesting
registration of Registrable Securities and (ii) a letter dated such date, from
the independent certified public accountants of the Company, in form and
substance as is customarily given by independent certified public accountants to
underwriters in an underwritten public offering, addressed to the underwriters,
if any, and to the Holders requesting registration of Registrable Securities.

         1.5      FURNISH INFORMATION. It shall be a condition precedent to the
obligations of the Company to take any action pursuant to this Section 1 with
respect to the Registrable Securities of any selling Holder that such Holder
shall furnish to the Company such information regarding itself, the Registrable
Securities held by it, and the intended method of disposition of such securities
as shall be required to effect the registration of such Holder's Registrable
Securities.


                                       5.

<PAGE>

         1.6      EXPENSES OF DEMAND REGISTRATION. All expenses other than
underwriting discounts and commissions incurred in connection with
registrations, filings or qualifications pursuant to Section 1.2, including
(without limitation) all registration, filing and qualification fees, printers'
and accounting fees, fees and disbursements of counsel for the Company and the
reasonable fees and disbursements of one counsel for the selling Holders shall
be borne by the Company; provided, however that the Company shall not be
required to pay for any expenses of any registration proceeding begun pursuant
to Section 1.2 if the registration request is subsequently withdrawn at the
request of the Holders of a majority of the Registrable Securities to be
registered (in which case all participating Holders shall bear such expenses),
unless the Holders of a majority of the Registrable Securities agree to forfeit
their right to one demand registration pursuant to Section 1.2; provided
further, however, that if at the time of such withdrawal, the Holders have
learned of a material adverse change in the condition, business, or prospects of
the Company from that known to the Holders at the time of their request and have
withdrawn the request with reasonable promptness following disclosure by the
Company of such material adverse change, then the Holders shall not be required
to pay any of such expenses and shall retain their rights pursuant to Section
1.2.

         1.7      EXPENSES OF COMPANY REGISTRATION. The Company shall bear and
pay all expenses incurred in connection with any registration, filing or
qualification of Registrable Securities with respect to the registrations
pursuant to Section 1.3 for each Holder (which right may be assigned as provided
in Section 1.13), including (without limitation) all registration, filing and
qualification fees, printers and accounting fees relating or apportionable
thereto and the fees and disbursements of one counsel for the selling Holders
selected by them, but excluding underwriting discounts and commissions relating
to Registrable Securities.

         1.8      UNDERWRITING REQUIREMENTS. In connection with any offering
involving an underwriting of shares of the Company's capital stock, the Company
shall not be required under Section 1.3 to include any of the Holders'
securities in such underwriting unless they accept the terms of the underwriting
as agreed upon between the Company and the underwriters selected by it (or by
other persons entitled to select the underwriters), and then only in such
quantity as the underwriters determine in their sole discretion will not
jeopardize the success of the offering by the Company. If the total amount of
securities, including Registrable Securities, requested by stockholders to be
included in such offering exceeds the amount of securities sold other than by
the Company that the underwriters determine in their sole discretion is
compatible with the success of the offering, then the Company shall be required
to include in the offering only that number of such securities, including
Registrable Securities, which the underwriters determine in their sole
discretion will not jeopardize the success of the offering (the securities so
included to be apportioned pro rata among the selling stockholders according to
the total amount of securities entitled to be included therein owned by each
selling stockholder or in such other proportions as shall mutually be agreed to
by such selling stockholders) but in no event shall (i) the amount of securities
of the selling Holders included in the offering be reduced below twenty percent
(20%) of the total amount of securities included in such offering, or (ii)
notwithstanding (i) above, any shares being sold by a stockholder exercising a
demand registration right similar to that granted in Section 1.2 be excluded
from such offering. For purposes of the preceding parenthetical concerning
apportionment, for any selling stockholder which is a Holder of Registrable
Securities and which is a partnership or corporation, the partners, retired
partners and stockholders of such Holder, or the estates and family members of
any such partners and retired partners and any trusts for the benefit of any of
the foregoing persons shall be deemed to be a


                                       6.

<PAGE>

single "selling stockholder," and any pro-rata reduction with respect to such
"selling stockholder," shall be based upon the aggregate amount of shares
carrying registration rights owned by all entities and individuals included in
such "selling stockholder," as defined in this sentence.

         1.9      DELAY OF REGISTRATION. No Holder shall have any right to
obtain or seek an injunction restraining or otherwise delaying any such
registration as the result of any controversy that might arise with respect to
the interpretation or implementation of this Section 1.

         1.10     INDEMNIFICATION. In the event any Registrable Securities are
included in a registration statement under this Section 1:

                         (a)    To the extent permitted by law, the Company will
indemnify and hold harmless each Holder, any underwriter (as defined in the Act)
for such Holder and each person, if any, who controls such Holder or underwriter
within the meaning of the Act or the 1934 Act, against any losses, claims,
damages or liabilities (joint or several) to which they may become subject under
the Act, the 1934 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 (each, a
"Violation"): (i) 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, (ii) 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 (iii) any violation or alleged violation by the
Company of the Act, the 1934 Act, any state securities law or any rule or
regulation promulgated under the Act, or the 1934 Act or any state securities
law; and the Company will pay to each such Holder, underwriter or controlling
person, as incurred, any legal or other expenses reasonably incurred by them in
connection with investigating or defending any such loss, claim, damage,
liability or action; provided, however, that the indemnity agreement contained
in this subsection 1.10(a) 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 Company (which consent shall not be unreasonably
withheld), nor shall the Company be liable in any such 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 any such Holder, underwriter or controlling person.

                         (b)    To the extent permitted by law, each selling
Holder will indemnify and hold harmless the Company, each of its directors, each
of its officers who has signed the registration statement, each person, if any,
who controls the Company within the meaning of the Act, any underwriter, any
other Holder selling securities in such registration statement and any
controlling person of any such underwriter or other Holder, against any losses,
claims, damages or liabilities (joint or several) to which any of the foregoing
persons may become subject, under the Act, or the 1934 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 (and only 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 will pay, as
incurred, any legal or other expenses reasonably incurred by any person intended
to be indemnified pursuant to this subsection


                                       7.

<PAGE>

1.10(b), in connection with investigating or defending any such loss, claim,
damage, liability or action; provided, however, that the indemnity agreement
contained in this subsection 1.10(b), 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, that, in no event shall any indemnity
under this subsection 1.10(b) exceed the gross proceeds from the offering
received by such Holder.

                         (c)    Promptly after receipt by an indemnified party
under this Section 1.10 of notice of the commencement of any action (including
any governmental action), such indemnified party will, if a claim in respect
thereof is to be made against any indemnifying party under this Section 1.10,
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
(together with all other indemnified parties which may be represented without
conflict by one counsel) shall have the right to retain one separate 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
1.10, but the omission so to deliver written notice to the indemnifying party
will not relieve it of any liability that it may have to any indemnified party
otherwise than under this Section 1.10.

                         (d)    If the indemnification provided for in this
Section 1.10 is held by a court of competent jurisdiction to be unavailable to
an indemnified party with respect to any loss, liability, claim, damage or
expense referred to therein, then the indemnifying party, in lieu of
indemnifying such indemnified party hereunder, shall contribute to the amount
paid or payable by such indemnified party as a result of such loss, liability,
claim, damage or expense in such proportion as is appropriate to reflect the
relative fault of the indemnifying party on the one hand and of the indemnified
party on the other in connection with the statements or omissions that resulted
in such loss, liability, claim, damage or expense as well as any other relevant
equitable considerations. The relative fault of the indemnifying party and of
the indemnified party shall be determined by reference to, among other things,
whether the untrue or alleged untrue statement of a material fact or the
omission to state a material fact relates to information supplied by the
indemnifying party or by the indemnified party and the parties' relative intent,
knowledge, access to information, and opportunity to correct or prevent such
statement or omission.

                         (e)    Notwithstanding the foregoing, to the extent
that the provisions on indemnification and contribution contained in the
underwriting agreement entered into in connection with the underwritten public
offering are in conflict with the foregoing provisions, the provisions in the
underwriting agreement shall control.

                         (f)    The obligations of the Company and Holders under
this Section 1.10 shall survive the completion of any offering of Registrable
Securities in a registration statement under this Section 1, and otherwise.


                                       8.

<PAGE>

         1.11     REPORTS UNDER SECURITIES EXCHANGE ACT OF 1934. With a view to
making available to the Holders the benefits of Rule 144 promulgated under the
Act and any other rule or regulation of the SEC that may at any time permit a
Holder to sell securities of the Company to the public without registration or
pursuant to a registration on Form S-3, the Company agrees to:

                         (a)    make and keep public information available, as
those terms are understood and defined in SEC Rule 144, at all times after
ninety (90) days after the effective date of the first registration statement
filed by the Company for the offering of its securities to the general public;

                         (b)    take such action, including the voluntary
registration of its Common Stock under Section 12 of the 1934 Act, as is
necessary to enable the Holders to utilize Form S-3 for the sale of their
Registrable Securities, such action to be taken as soon as practicable after the
end of the fiscal year in which the first registration statement filed by the
Company for the offering of its securities to the general public is declared
effective;

                         (c)    file with the SEC in a timely manner all reports
and other documents required of the Company under the Act and the 1934 Act; and

                         (d)    furnish to any Holder, so long as the Holder
owns any Registrable Securities, forthwith upon request (i) a written statement
by the Company that it has complied with the reporting requirements of SEC Rule
144 (at any time after ninety (90) days after the effective date of the first
registration statement filed by the Company), the Act and the 1934 Act (at any
time after it has become subject to such reporting requirements), or that it
qualifies as a registrant whose securities may be resold pursuant to Form S-3
(at any time after it so qualifies), (ii) a copy of the most recent annual or
quarterly report of the Company and such other reports and documents so filed by
the Company, and (iii) such other information as may be reasonably requested in
availing any Holder of any rule or regulation of the SEC which permits the
selling of any such securities without registration or pursuant to such form.

         1.12     FORM S-3 REGISTRATION. In case the Company shall receive from
any Holder who holds more than two percent (2%) of the Company's outstanding
stock a written request that the Company effect a registration on Form S-3 and
any related qualification or compliance with respect to all or a part of the
Registrable Securities owned by such Holder, the Company will:

                         (a)  promptly give written notice of the proposed
registration, and any related qualification or compliance, to all other Holders;
and

                         (b)    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
Holder's or 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 fifteen (15) 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
1.12: (1) if Form S-3 is not available for such offering by the Holders; (2) if
the Holders, together with the holders of any other securities of the Company
entitled to inclusion in such registration, propose to sell Registrable
Securities and such other securities (if


                                       9.

<PAGE>

any) at an aggregate price to the public (net of any underwriters' discounts or
commissions) of less than $1,000,000; (3) if the Company shall furnish to the
Holders a certificate signed by the President of the Company stating that, in
the good faith judgment of the Board of Directors of the Company, it would be
seriously detrimental to the Company and its stockholders for such Form S-3
registration to be effected 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 sixty (60) days after receipt of the request of the
Holder or Holders under this Section 1.12; provided, however, that the Company
shall not utilize this right more than once in any twelve-month period; (4) if
the Company has already effected three registrations on Form S-3 for the Holders
pursuant to this Section 1.12; or (5) 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 of
compliance.

                         (c)    Subject to the foregoing, the Company shall file
a registration statement covering the Registrable Securities and other
securities so requested to be registered as soon as practicable after receipt of
the request or requests of the Holders. All expenses incurred in connection with
a registration requested pursuant to this Section 1.12, including (without
limitation) all registration, filing, qualification, printer's and accounting
fees and the reasonable fees and disbursements of counsel for the selling Holder
or Holders and counsel for the Company, but excluding any underwriters'
discounts or commissions associated with Registrable Securities, shall be borne
by the Company. Registrations effected pursuant to this Section 1.12 shall not
be counted as demands for registration or registrations effected pursuant to
Sections 1.2 or 1.3, respectively.

         1.13 ASSIGNMENT OF REGISTRATION RIGHTS. The rights to cause the
Company to register Registrable Securities pursuant to this Section 1 may be
assigned (but only with all related obligations) by a Holder to a transferee
or assignee of such securities who, after such assignment or transfer, holds
at least 500,000 shares of Registrable Securities (subject to appropriate
adjustment for stock splits, stock dividends, combinations and other
recapitalizations), provided: (a) the Company is, within a reasonable time
after such transfer, furnished with written notice of the name and address of
such transferee or assignee and the securities with respect to which such
registration rights are being assigned; (b) such transferee or assignee
agrees in writing to be bound by and subject to the terms and conditions of
this Agreement, including without limitation the provisions of Section 1.15
below; and (c) such assignment shall be effective only if immediately
following such transfer the further disposition of such securities by the
transferee or assignee is restricted under the Act. For the purposes of
determining the number of shares of Registrable Securities held by a
transferee or assignee, the holdings of transferees and assignees of a
partnership who are partners or retired partners of such partnership
(including spouses and ancestors, lineal descendants and siblings of such
partners or spouses who acquire Registrable Securities by gift, will or
intestate succession) shall be aggregated together and with the partnership;
provided that all assignees and transferees who would not qualify
individually for assignment of registration rights shall have a single
attorney-in-fact for the purpose of exercising any rights, receiving notices
or taking any action under Section 1.

         1.14     LIMITATIONS ON SUBSEQUENT REGISTRATION RIGHTS. From and after
the date of this Agreement, the Company shall not, without the prior written
consent of the Holders of sixty-six and two-thirds percent (66-2/3%) of the
outstanding Registrable Securities, enter into any agreement with any holder or
prospective holder of any securities of the Company which would


                                      10.

<PAGE>

allow such holder or prospective holder (a) to include such securities in any
registration filed under Section 1.2 hereof, unless under the terms of such
agreement, such holder or prospective holder may include such securities in any
such registration only to the extent that the inclusion of his securities will
not reduce the amount of the Registrable Securities of the Holders which is
included or (b) to make a demand registration which could result in such
registration statement being declared effective prior to the earlier of either
of the dates set forth in subsection 1.2(a) or within one hundred twenty (120)
days of the effective date of any registration effected pursuant to Section 1.2.

         1.15     "MARKET STAND-OFF" AGREEMENT. Each Investor hereby agrees
that, during the period of duration specified by the Company and an underwriter
of common stock or other securities of the Company, following the effective date
of a registration statement of the Company filed under the Act, it shall not, to
the extent requested by the Company and such underwriter, directly or indirectly
sell, offer to sell, contract to sell (including, without limitation, any short
sale), grant any option to purchase or otherwise transfer or dispose of (other
than to donees who agree to be similarly bound) any securities of the Company
held by it at any time during such period except common stock included in such
registration or common stock purchased after the effective date of the Company's
first registration statement filed under the Act which are purchased in an open
market transaction; provided, however, that:

                         (a)    such agreement shall be applicable only to the
first such registration statement of the Company which covers Common Stock (or
other securities) to be sold on its behalf to the public in an underwritten
offering; and

                         (b)    all officers and directors of the Company
(whether or not pursuant to this Agreement) enter into similar agreements; and

                         (c) such market stand-off time period shall not exceed
one hundred eighty (180) days.

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

                  Notwithstanding the foregoing, the obligations described in
this Section 1.15 shall not apply to a registration relating solely to employee
benefit plans on Form S-1 or Form S-8 or similar forms which may be promulgated
in the future, or a registration relating solely to a Commission Rule 145
transaction on Form S-14 or Form S-15 or similar forms which may be promulgated
in the future.

         1.16     TERMINATION OF REGISTRATION RIGHTS.

                         (a)    No Holder shall be entitled to exercise any
right provided for in this Section 1 after five (5) years following the
consummation of the sale of securities pursuant to a registration statement
filed by the Company under the Act in connection with the initial firm
commitment underwritten offering of its securities to the general public.

                         (b)    In addition, the right of any Holder to request
registration or inclusion in any registration pursuant to Section 1.3 shall
terminate on the closing of the first


                                      11.

<PAGE>

Company-initiated registered public offering of Common Stock of the Company if
all shares of Registrable Securities held or entitled to be held upon conversion
by such Holder may immediately be sold under Rule 144 during any 90-day period,
or on such date after the closing of the first Company-initiated registered
public offering of Common Stock of the Company as all shares of Registrable
Securities held or entitled to be held upon conversion by such Holder may
immediately be sold under Rule 144 during any 90-day period; provided, however,
that the provisions of this Section 1.16(b) shall not apply to any Holder who
owns more than one percent (1%) of the Company's outstanding stock until such
time as such Holder owns less than one percent (1%) of the outstanding stock of
the Company.

2.       COVENANTS OF THE COMPANY.

         2.1      DELIVERY OF FINANCIAL STATEMENTS. The Company shall deliver to
each Investor:

                         (a)    who holds at least 500,000 shares of Series B,
Series C, Series D, Series E, Series F, Series G or Series H Preferred Stock or
Common Stock issued upon conversion thereof (as adjusted for subsequent stock
splits, recombinations or reclassifications), as soon as practicable, but in any
event within ninety (90) days after the end of each fiscal year of the Company,
an income statement for such fiscal year, a balance sheet of the Company and
statement of stockholder's equity as of the end of such year and a statement of
cash flows for such year, such year-end financial reports to be in reasonable
detail, prepared in accordance with generally accepted accounting principles
("GAAP"), and audited and certified by independent public accountants of
nationally recognized standing selected by the Company; and

                         (b)    who holds at least 850,000 shares of Series B,
Series C, Series D, Series E, Series F, Series G or Series H Preferred Stock or
Common Stock issued upon conversion thereof (as adjusted for subsequent stock
splits, recombinations or reclassifications) (a "Major Investor"):

                                (i)      as soon as practicable, but in any
event within forty-five (45) days after the end of each of the first three (3)
quarters of each fiscal year of the Company, an unaudited profit or loss
statement, statement of cash flows for such fiscal quarter and an unaudited
balance sheet as of the end of such fiscal quarter;

                                (ii)     within thirty (30) days of the end of
each month, an unaudited income statement, statement of cash flows and balance
sheet for and as of the end of such month, in reasonable detail;

                                (iii)    as soon as practicable, but in any
event thirty (30) days prior to the end of each fiscal year, a budget and
business or operating plan for the next fiscal year in the form approved by the
Board of Directors of the Company, prepared on a monthly basis including balance
sheets and sources and applications of funds statements for such months and, as
soon as prepared, any other budgets or revised budgets prepared by the Company;

                                (iv)     with respect to the financial
statements called for in subsections (i) and (ii) of this Section 2.1(b), an
instrument executed by the Chief Financial Officer or President of the Company
and certifying that such financials were prepared in accordance with GAAP
consistently applied with prior practice for earlier periods (with the


                                      12.

<PAGE>

exception of footnotes that may be required by GAAP) and fairly present the
financial condition of the Company and its results of operation for the period
specified, subject to year-end audit adjustment;

                                (v)      such other information relating to the
financial condition, business, prospects or corporate affairs of the Company as
the Major Investor or any assignee of the Major Investor may from time to time
request, provided, however, that the Company shall not be obligated under this
subsection (v) or any other subsection of Section 2.1 to provide information
which it deems in good faith to be a trade secret or similar confidential
information.

         2.2      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 and outside accountants, all at such
reasonable times as may be requested by such Major Investor; provided, however,
that the Company shall not be obligated pursuant to this Section 2.2 to provide
access to any information which it reasonably considers to be a trade secret or
similar confidential information.

         2.3      RIGHT OF FIRST OFFER. Subject to the terms and conditions
specified in this Section 2.4, the Company hereby grants to each Major Investor
a right of first offer with respect to future sales by the Company of its Shares
(as hereinafter defined). For purposes of this Section 2.4, Major Investor
includes any general partners and affiliates of a Major Investor. A Major
Investor shall be entitled to apportion the right of first offer hereby granted
it among itself and its partners and affiliates in such proportions as it deems
appropriate.

                  Each time the Company proposes to offer any shares of, or
securities convertible into or exercisable for any shares of, any class of its
capital stock ("Shares"), the Company shall first make an offering of such
Shares to each Major Investor in accordance with the following provisions:

                         (a)    The Company shall deliver a notice by certified
mail ("Notice") to the Major Investors stating (i) its bona fide intention to
offer such Shares, (ii) the number of such Shares to be offered, and (iii) the
price and terms, if any, upon which it proposes to offer such Shares.

                         (b)    Within twenty (20) calendar days after receipt
of the Notice, each Major Investor may elect to purchase or obtain, at a price
and on the terms specified in the Notice, up to that portion of such Shares
which equals the proportion that the number of shares of Common Stock issued and
held, or issuable upon conversion of the Series A, Series B, Series C, Series D,
Series E, Series F, Series G and Series H Preferred Stock then held, by such
Major Investor bears to the total number of shares of Common Stock of the
Company then outstanding (assuming full conversion of all convertible
securities). The Company shall promptly, in writing, inform each Major Investor
which purchases all the shares available to it ("Fully-Exercising Investor") of
any other Major Investor's failure to do likewise. During the ten-day period
commencing after receipt of such information, each Fully-Exercising Investor
shall be entitled to obtain that portion of the Shares for which Major Investors
were entitled to subscribe but which were not subscribed for by the Major
Investors which is equal to the proportion that the number of shares of Common
Stock issued and held, or issuable upon conversion of Series A, Series B,


                                      13.

<PAGE>

Series C, Series D, Series E, Series F, Series G and Series H Preferred Stock
then held, by such Fully-Exercising Investor bears to the total number of shares
of Common Stock issued and held, or issuable upon conversion of the Series A,
Series B, Series C, Series D, Series E, Series F, Series G and Series H
Preferred Stock then held, by all Fully-Exercising Investors who wish to
purchase some of the unsubscribed shares.

                         (c)    If all Shares which Investors are entitled to
obtain pursuant to subsection 2.4(b) are not elected to be obtained as provided
in subsection 2.4(b) hereof, the Company may, during the 30-day period following
the expiration of the period provided in subsection 2.4(b) hereof, offer the
remaining unsubscribed portion of such Shares to any person or persons at a
price not less than, and upon terms no more favorable to the offeree than those
specified in the Notice. If the Company does not enter into an agreement for the
sale of the Shares within such period, or if such agreement is not consummated
within thirty (30) days of the execution thereof, the right provided hereunder
shall be deemed to be revived and such Shares shall not be offered unless first
reoffered to the Major Investors in accordance herewith.

                         (d)    The right of first offer in this Section 2.4
shall not be applicable (i) to the issuance or sale of not to exceed 9,047,108
shares of Common Stock (or options therefor) to members of the Company's
Scientific Advisory Board, consultants or employees for the primary purpose of
soliciting or retaining their employment or services, (ii) to or after
consummation of a bona fide, firmly underwritten public offering of shares of
common stock, registered under the Act pursuant to a registration statement on
Form S-1, the aggregate offering price of which exceeds $25,000,000 in the
aggregate, (iii) to the issuance of securities pursuant to the conversion or
exercise of convertible or exercisable securities, (iv) to the issuance of
securities as consideration payable to the sellers in connection with a bona
fide business acquisition of or by the Company, whether by merger,
consolidation, sale of assets, sale or exchange of stock or otherwise, or (v) to
the issuance or sale of shares of Series H Preferred Stock pursuant to the Stock
Purchase Agreement.

                         (e)    The right of first offer set forth in this
Section 2.4 may not be assigned or transferred, except that (i) such right is
assignable by each Major Investor to any wholly owned subsidiary or parent of,
or to any corporation or entity that is, within the meaning of the Act,
controlling, controlled by or under common control with, any such Major
Investor, and (ii) such right is assignable between and among any of the Major
Investors.

         2.4      IRC SECTION 305. So long as any shares of Series B Preferred
Stock, Series C Preferred Stock, Series D Preferred Stock or Series H Preferred
Stock remain outstanding, the Company will not, without approval of holders of a
majority of the Series B Preferred Stock, Series C Preferred Stock, Series D
Preferred Stock, or Series H Preferred Stock, respectively, then outstanding, do
any act or thing which would result in taxation of the holders of shares of the
Series B Preferred Stock, Series C Preferred Stock, Series D Preferred Stock or
Series H Preferred Stock, respectively, under Section 305 of the Internal
Revenue Code of 1986, as amended (or any comparable provision of the Internal
Revenue Code as hereafter from time to time amended).

         2.5      KEY-PERSON INSURANCE. As of the date hereof, the Company shall
have from financially sound and reputable insurers term life insurance on the
life of Kenneth J. Kelley in the amount of $1,000,000 and on the life of John
Fiddes in the amount of $1,000,000, except as


                                      14.

<PAGE>

otherwise decided in accordance with policies adopted by the Company's Board of
Directors. The Company will cause to be maintained the term life insurance
required by this Section 2.6, except as otherwise decided in accordance with
policies adopted by the Company's Board of Directors. Such policies shall name
the Company as loss payee and shall not be cancelable by the Company without
prior approval of the Board of Directors.

         2.6      CONFIDENTIALITY AGREEMENTS. The Company shall use its best
efforts to cause all outside service providers of the Company to enter into the
Company's standard form of confidentiality agreement and to prevent any
violations of such agreements by such service providers.

         2.7      ANNOUNCEMENTS. So long as Investor (Guernsey) Ltd. Or its
Affiliates as defined herein ("Investors Guernsey") is a stockholder of the
Company, the Company shall not make any public announcement with respect to the
Stock Purchase Agreement or the transactions contemplated thereby, without the
prior written consent of Investor Guernsey, except (i) pursuant to a press
release mutually agreeable to the Company and Investor Guernsey in connection
with the closing of the transactions contemplated by the Stock Purchase
Agreement; (ii) the disclosure of the identity of any Investor as a stockholder
of the Company; or (iii) as otherwise required by applicable laws, rules or
regulations.

         2.8      TRANSACTIONS WITH AFFILIATES. The Company shall not engage in
any transaction with a director, officer or employee of the Company or an
affiliate of director, officer or employee of the Company unless the transaction
is on terms no less favorable than those that would exist in an arm's-length
transaction and is approved by a majority of the directors of the Company who do
not have an interest in the transaction and except for transactions related to
the compensation or employment of such director, officer or employee.

         2.9      ISSUANCE OF SERIES H PREFERRED STOCK. The Company shall not
issue any shares, or rights to acquire shares, of Series H Preferred Stock other
than the Series H Preferred Stock and warrant to purchase Series H Preferred
Stock to be issued pursuant to the Stock Purchase Agreement and an additional
aggregate amount of 100,000 shares of Series H Preferred Stock (as adjusted for
stock splits, combinations, recapitalizations and the like) to be issued in
connection with any equipment leasing or loan arrangement or debt financing from
a bank or similar financial institution. The authorized number of shares of
Series H Preferred Stock shall not exceed 7,600,000 shares (as adjusted for
stock splits, combinations, recapitalizations and the like).

         2.10     TERMINATION OF COVENANTS. The covenants set forth in
subsections 2.1(b) through 2.9 (other than subsection 2.7) shall terminate and
be of no further force or effect when the sale of securities pursuant to a
registration statement filed by the Company under the Act in connection with the
firm commitment underwritten offering of its securities to the general public is
consummated or when the Company first becomes subject to the periodic reporting
requirements of Sections 12(g) or 15(d) of the 1934 Act, whichever event shall
first occur.

3.       MISCELLANEOUS.

         3.1      SUCCESSORS AND ASSIGNS. Except as otherwise provided herein,
the terms and conditions of this Agreement shall inure to the benefit of and be
binding upon the respective


                                      15.

<PAGE>

successors and assigns of the parties (including transferees of any shares of
Registrable Securities). Nothing in this Agreement, express or implied, is
intended to confer upon any party other then the parties hereto or their
respective successors and assigns any rights, remedies, obligations, or
liabilities under or by reason of this Agreement, except as expressly provided
in this Agreement.

         3.2      GOVERNING LAW. This Agreement shall be governed by and
construed under the laws of the State of California as applied to agreements
among California residents entered into and to be performed entirely within
California.

         3.3      COUNTERPARTS. This Agreement may be executed in two or more
counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.

         3.4      TITLES AND SUBTITLES. The titles and subtitles used in this
Agreement are used for convenience only and are not to be considered in
construing or interpreting this Agreement.

         3.5      NOTICES. Unless otherwise provided, any notice required or
permitted under this Agreement shall be given in writing and shall be deemed
effectively given: (i) upon personal delivery to the party to be notified; (ii)
when sent by confirmed facsimile; or (iii) upon deposit with an overnight or
similar courier service and addressed to the party to be notified at the address
indicated for such party on the signature page hereof or on the Company's
records, or at such other address as such party may designate by ten (10) days'
advance written notice to the other parties.

         3.6      EXPENSES. If any action at law or in equity is necessary to
enforce or interpret the terms of this Agreement, the prevailing party shall be
entitled to reasonable attorneys' fees, costs and necessary disbursements in
addition to any other relief to which such party may be entitled.

         3.7      AMENDMENTS AND WAIVERS. Any term of this Agreement may be
amended and the observance of any term of this Agreement may be waived (either
generally or in a particular instance and either retroactively or
prospectively), only with the written consent of the Company and the holders of
sixty-six and two-thirds percent (66-2/3%) of the Registrable Securities then
outstanding; provided, however, that subsections 2.7 and 2.9 shall not be
amended without the prior written consent of Investor Guernsey. Any amendment or
waiver effected in accordance with this paragraph shall be binding upon each
holder of any Registrable Securities then outstanding, each future holder of all
such Registrable Securities and the Company.

         3.8      SEVERABILITY. If one or more provisions of this Agreement are
held to be unenforceable under applicable law, such provision shall be excluded
from this Agreement and the balance of the Agreement shall be interpreted as if
such provision were so excluded and shall be enforceable in accordance with its
terms.

         3.9      AGGREGATION OF STOCK. All shares of Registrable Securities
held or acquired by affiliated entities or persons shall be aggregated together
for the purpose of determining the availability of any rights under this
Agreement.

         3.10     ENTIRE AGREEMENT. This Agreement (including the Exhibits and
Schedules hereto, if any) constitutes the full and entire understanding and
agreement between the parties


                                      16.

<PAGE>

with regard to the subjects hereof and thereof. This Agreement hereby amends and
restates the Existing Agreement in its entirety.

                            [Signature page follows]


                                      17.

<PAGE>


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

                                     INTRABIOTICS PHARMACEUTICALS, INC.

                                     BY:  /s/ Kenneth J. Kelley
                                        ---------------------------------------
                                          NAME:  Kenneth J. Kelley
                                          TITLE:  President

                                     ADDRESS:    1255 Terra Bella
                                                 Mountain View, CA 94043

                                     INVESTOR (GUERNSEY) LTD.

                                     BY: /s/ David Jeffreys /s/ Marc Hollander
                                         --------------------------------------
                                     NAME: David Jeffreys and Marc Hollander
                                          -------------------------------------
                                     TITLE: Director
                                           ------------------------------------
                                     ADDRESS:    National Westminster House
                                                 Le Truchot, St. Peter Port
                                                 Guernsey, Channel Islands
                                                 GYI 4PW United Kingdom

                                     AND:

                                     O'Sullivan Graev & Karabell, LLP
                                     30 Rockefeller Plaza, 24th Floor
                                     New York, NY  10112
                                     Telephone:  (212) 408-2400
                                     Facsimile:  (212) 728-5950
                                     Attn:  Harvey M. Eisenberg, Esq.


                                 Signature Page
                            Investor Rights Agreement
                       IntraBiotics Pharmaceuticals, Inc.

<PAGE>

                                      VULCAN VENTURES, INC.

                                      BY:  /s/ William D. Savoy
                                         ---------------------------------------
                                      NAME: William D. Savoy
                                           -------------------------------------
                                      TITLE: Vice President
                                           -------------------------------------
                                      ADDRESS:    110 110th Avenue, N.E.
                                                  Suite 550
                                                  Bellevue, WA  98004
                                                  Attn:  William  H. Savoy

                                      NEW ENGLAND PARTNERS CAPITAL, L.P.
                                      By:  NEP Capital, Inc, General Partner
                                         ---------------------------------------
                                      BY:  /s/ John Rousseau
                                         ---------------------------------------
                                           NAME: John Rousseau
                                                --------------------------------
                                           TITLE: President
                                                 -------------------------------
                                      ADDRESS:     One Boston Place
                                                   Suite 2100
                                                   Boston, MA  02108
                                                   Attn:  John Rousseau
                                      /s/ Jonathan Reingold
                                      ------------------------------------------
                                      JONATHAN REINGOLD

                                      ADDRESS:     9403 N.E. 26th Street
                                                   Bellevue, WA  98004


                                 Signature Page
                            Investor Rights Agreement
                       IntraBiotics Pharmaceuticals, Inc.

<PAGE>

                                      ------------------------------------------
                                      Investor Name

                                      By:
                                         ---------------------------------------

                                      ------------------------------------------
                                      Printed Name/Title

                                      Address:
                                              ----------------------------------
                                              ----------------------------------
                                              ----------------------------------
                                              ----------------------------------


                                 Signature Page
                            Investor Rights Agreement
                       IntraBiotics Pharmaceuticals, Inc.

<PAGE>

                       SCHEDULE A - SCHEDULE OF INVESTORS

SERIES A PREFERRED STOCK


INVESTOR

Herb L. Heyneker
Howard B. Rosen
John J. Lauter, Jr.
John Selling
Jonathan J. MacQuitty
Leland F. Wilson
Michael F. Bigham
Michael J. Ross
Patrick O'Connor
Paul R. De Stefano
P&E Ventures
Richard Miller
DLJ Capital Corp.
Sprout Capital VI, L.P.

SERIES B PREFERRED STOCK

INVESTOR

Sprout Capital VI, L.P.
DLJ Capital Corp.
St. Paul Fire and Marine Insurance Company
Brinson MAP Venture Capital Fund III
Brinson Venture Capital Fund III, L.P.
Nancy Olson
Becket & Company, Inc.
Steve Burrill

SERIES C PREFERRED STOCK -- FIRST CLOSING (APRIL 10, 1996)

INVESTOR

Brinson Venture Capital Fund, III, L.P.
Brinson MAP Venture Capital Fund III
Sprout Capital VII, L.P.
St. Paul Fire and Marine Insurance Company
New York Life Insurance Company
Singapore Bio-Innovations Pte. Ltd.
Sextant Group, Inc.
John C. Hou


                                      A-1.

<PAGE>

SERIES C PREFERRED STOCK -- SECOND CLOSING (JUNE 20, 1996)

INVESTOR

Sprout Capital VI, L.P.
Sprout Capital VII, L.P.
Sprout CEO Fund, L.P.
DLJ Capital Corp.
IASD Health Services Corp.
Michael J. Ross
Robert R. Tillman Living Trust
John Selling and Lydia Selling
Edward S. Andrle
Herbert L. Heyneker
Michael F. Bigham

SERIES D PREFERRED STOCK

INVESTOR

Edward Andrle
Lawrence Bowman
Brinson MAP Venture Capital Fund III, L.P.
Brinson Venture Capital Fund III, L.P.
DLJ Capital Corp.
IASD Health Services Corporation
New York Life Insurance Company
Peter Frederick & Jane Elizabeth Carpenter
 TTEE Carpenter 1985 Irrevocable Trust
 dated 4/29/85, Jane Shaw, Trustee28,572
Prince Capital Master Fund, L.P.
John Selling
Singapore Bio-Innovations Pte. Ltd.
Spinnaker Technology Fund, L.P.
Spinnaker Technology Offshore Fund, Ltd.
Sprout Capital VI, L.P.
Sprout Capital VII, L.P.
Sprout CEO Fund
St. Paul Venture Capital IV LLC
Dr. Lance Willsey

SERIES E PREFERRED STOCK


INVESTOR

Spinnaker Technology Fund, L.P.
Spinnaker Technology Offshore Fund, Ltd.
Spinnaker Founders Fund, L.P.
Spinnaker Clipper Fund, L.P.


                                      A-2.

<PAGE>

SERIES F PREFERRED STOCK

INVESTOR

Pharmacia & Upjohn S.p.A.
Biosearch Italia S.p.A.

SERIES G PREFERRED STOCK

INVESTORS

Arnold S. & Bette G. Joffman, JTWROS
ASX 11036 ApS
Paul Bancroft
Bank Julius Baer & Co. Ltd. Custodian for
   International BM biomedicine Holdings Inc.
Bent Kjeldahl ApS
Peper Bohnsen
Helge Bom
Darlene and David Bossen
Peter Bracken
James Brinkley
Peter Clausen
Eva Falck Crone
Curran Partners L.P.
Danica Aktieinvest ApS
Donald L. Dell
Robert Donovan
Lindsey D. Dryden
E.M. Marketing ApS
Eaton Vance Worldwide Health Services Fund
Beatrice G. Fuchs
Peter S. Garcia
Harris Antibiotic Partners
Richard Himelfarb
Iron Block Partners, LLC
William B. Jones
Henry E. Jorgensen
Kaufmann Fund, Inc.
Lars-Erik Houmann Christensen ApS
John J. Lauter, Jr.
Legg Mason Custodian fbo Stephen C. Eastham
  Money Purchase Plan
Seth J. Lehr
Landsnakke A/A
Norman Lockshin
Daniel Luczak
Raymond A. Mason
MarvinMcIntyre
Donald Metzger
MLRS Investment Associates, LLC


                                      A-3.

<PAGE>

Chr. V. Nellemann
New England Parnters Capital, L.P.
Henrik Norling
Hans Jorgen Petersen
Jens Poulsen
Preben Bech ApS
Jonathen Reingold
David Reznick
Robert Sabelhaus
Martin J. Salzman
Scanhybrid ApS
Hanne Schaldemose
Brian E. Schindler
Sears Family Trust, California Living
  Trust DTD 3/11/91
Richard Sharp
Niels Henrik Sliben
Alexsander Stewart
Gary Sudhalter
Stephen Sudovar
Per Lund Thoft
Topholm & Westerman Holding ApS Ny
   Vestergaardsvej 25
Soren Truelsen
Vulcan Ventures, Inc.
Soren Erik Westermann


SERIES H PREFERRED STOCK - FIRST CLOSING (OCTOBER 15, 1999)

INVESTORS

Vulcan Ventures, Inc.
New England Partners Capital, L.P.
Jonathan Reingold

SERIES H PREFERRED STOCK - SECOND CLOSING (NOVEMBER 3, 1999)

INVESTORS

Investor (Guernsey) Ltd.


                                      A-4.