Exhibit 4.2




                          REGISTRATION RIGHTS AGREEMENT


                                  BY AND AMONG


                                    XOMA LTD.


                                   AS ISSUER,


                                       AND


                          J.P. MORGAN SECURITIES INC.,
                              ADAMS HARKNESS, INC,
                         DEUTSCHE BANK SECURITIES, INC.,
                           FIRST ALBANY CAPITAL, INC.,
                                       AND
                            JEFFERIES & COMPANY, INC.


                              AS INITIAL PURCHASERS


                          DATED AS OF FEBRUARY 7, 2005





<PAGE>


     THIS REGISTRATION RIGHTS AGREEMENT (the "Agreement") is made and entered
into as of February 7, 2005, by and among XOMA Ltd., a Bermuda company (the
"Company"), and J.P. Morgan Securities Inc., Adams Harkness, Inc., Deutsche Bank
Securities, Inc., First Albany Capital Inc. and Jefferies & Company
(collectively, the "Initial Purchasers") pursuant to the Purchase Agreement,
dated February 1, 2005, among the Company and the Initial Purchasers (the
"Purchase Agreement").

     In order to induce the Initial Purchasers to enter into the Purchase
Agreement, the Company has agreed to provide the registration rights set forth
in this Agreement. The execution of this Agreement is a condition to the closing
under the Purchase Agreement.

     The Company agrees with the Initial Purchasers (i) for their benefit as
Initial Purchasers and (ii) for the benefit of the beneficial owners (including
the Initial Purchasers) from time to time of the Notes (as defined herein) and
the beneficial owners from time to time of the Underlying Common Shares (as
defined herein) issued upon conversion of the Notes (each of the foregoing a
"Holder" and together the "Holders"), as follows:

     Section 1. Definitions. Capitalized terms used herein without definition
shall have their respective meanings set forth in the Purchase Agreement. As
used in this Agreement, the following terms shall have the following meanings:

     "Affiliate" means with respect to any specified person, an "affiliate," as
defined in Rule 144, of such person.

     "Amendment Effectiveness Deadline Date" has the meaning set forth in
Section 2(d) hereof.

     "Applicable Conversion Price" as of any date of determination means the
Conversion Price in effect as of such date of determination or, if no Notes are
then outstanding, the Conversion Price that would be in effect were Notes then
outstanding.

     "Business Day" means each Monday, Tuesday, Wednesday, Thursday and Friday
that is not a day on which banking institutions in The City of New York are
authorized or obligated by law or executive order to close.

     "Common Shares" means the common shares, par value $0.0005 per share, of
the Company and any other common shares as may constitute "Common Shares" for
purposes of the Indenture, including the Underlying Common Shares.

     "Conversion Price" has the meaning assigned to such term in the Indenture.

     "Conversion Rate" has the meaning assigned to such term in the Indenture.



                                       2
<PAGE>

     "Damages Accrual Period" has the meaning set forth in Section 2(e) hereof.

     "Damages Payment Date" means each interest payment date under the Indenture
(provided that February 1, 2012, the maturity date of the Notes, shall also be a
Damages Payment Date) and each February 1 and August 1 in the case of the
Underlying Common Shares.

     "Deferral Notice" has the meaning set forth in Section 3(i) hereof.

     "Deferral Period" has the meaning set forth in Section 3(i) hereof.

     "Effectiveness Deadline Date" has the meaning set forth in Section 2(a)
hereof.

     "Effectiveness Period" means the period commencing on the last date of
original issuance of the Notes and terminating upon the earliest of the
following: (A) when all the Notes covered by the Shelf Registration Statement
cease to be outstanding or have been sold pursuant to the Shelf Registration
Statement or pursuant to Rule 144(k) under the Securities Act or when all Common
Shares issued upon conversion of any such Notes cease to be outstanding or have
been sold pursuant to the Shelf Registration Statement or pursuant to Rule
144(k) under the Securities Act and (B) when all outstanding Registrable
Securities (as defined below) held by persons that are not Affiliates of the
Company may be resold without registration under the Securities Act pursuant to
Rule 144(k) under the Securities Act or any successor provision thereto.

     "Event" has the meaning set forth in Section 2(e) hereof.

     "Event Date" has the meaning set forth in Section 2(e) hereof.

     "Exchange Act" means the Securities Exchange Act of 1934, as amended, and
the rules and regulations of the SEC promulgated thereunder.

     "Filing Deadline Date" has the meaning set forth in Section 2(a) hereof.

     "Holder" has the meaning set forth in the third paragraph of this
Agreement.

     "Indenture" means the Indenture, dated as of February 7, 2005, between the
Company and Wells Fargo Bank, National Association, as trustee, pursuant to
which the Notes are being issued.

     "Initial Purchasers" has the meaning set forth in the preamble hereof.

     "Initial Shelf Registration Statement" has the meaning set forth in Section
2(a) hereof.



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<PAGE>

     "Issue Date" means the first date of original issuance of the Notes.

     "Liquidated Damages Amount" has the meaning set forth in Section 2(e)
hereof.

     "Material Event" has the meaning set forth in Section 3(i) hereof.

     "Notes" means the 6.50% Convertible Senior Notes due 2012 of the Company to
be purchased pursuant to the Purchase Agreements.

     "Notice and Questionnaire" means a written notice delivered to the Company
containing substantially the information called for by the Selling
Securityholder Notice and Questionnaire attached as Annex A to the Offering
Memorandum of the Company dated February 1, 2005 relating to the Notes.

     "Notice Holder" means, on any date, any Holder that has delivered a Notice
and Questionnaire to the Company on or prior to such date, so long as all of
their Registrable Securities that have been registered for resale pursuant to a
Notice and Questionnaire have not been sold in accordance with a Registration
Statement.

     "Prospectus" means the prospectus included in any Registration Statement
(including, without limitation, a prospectus that discloses information
previously omitted from a prospectus filed as part of an effective registration
statement in reliance upon Rule 415 promulgated under the Securities Act), as
amended or supplemented by any amendment or prospectus supplement, including
post-effective amendments, and all materials incorporated by reference or
explicitly deemed to be incorporated by reference in such prospectus.

     "Purchase Agreement" has the meaning set forth in the preamble hereof.

     "Record Holder" means (i) with respect to any Damages Payment Date relating
to any Notes as to which any such Liquidated Damages Amount has accrued, the
holder of record of such Note on the record date with respect to the interest
payment date under the Indenture on which such Damages Payment Date shall occur
and (ii) with respect to any Damages Payment Date relating to the Underlying
Common Shares as to which any such Liquidated Damages Amount has accrued, the
registered holder of such Underlying Common Shares fifteen (15) days prior to
such Damages Payment Date.

     "Registrable Securities" means the Notes until such Notes have been
converted into or exchanged for the Underlying Common Shares and, at all times
the Underlying Common Shares and any securities into or for which such
Underlying Common Shares have been converted or exchanged, and any security
issued with respect thereto upon any bonus issue, share dividend, split,
subdivision or similar event until, in the case of any such security, (A) the
earliest of (i) its effective registration under the Securities Act and resale
in accordance with the Registration Statement covering it, (ii) except with
respect to Registrable



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<PAGE>

Securities held by an Affiliate of the Company, expiration of the holding period
that would be applicable thereto under Rule 144(k) or (iii) its sale to the
public pursuant to Rule 144 (or any similar provision then in force, but not
Rule 144A) under the Securities Act, and (B) as a result of the event or
circumstance described in any of the foregoing clauses (i) through (iii), the
legend with respect to transfer restrictions required under the Indenture is
removed or removable in accordance with the terms of the Indenture or such
legend, as the case may be.

     "Registration Expenses" has the meaning set forth in Section 5 hereof.

     "Registration Statement" means any registration statement of the Company
that covers any of the Registrable Securities pursuant to the provisions of this
Agreement including the Prospectus, amendments and supplements to such
registration statement, including post-effective amendments, all exhibits, and
all materials incorporated by reference or explicitly deemed to be incorporated
by reference in such registration statement.

     "Restricted Securities" has the meaning given such term in Rule 144.

     "Rule 144" means Rule 144 under the Securities Act, as such Rule may be
amended from time to time, or any similar rule or regulation hereafter adopted
by the SEC.

     "Rule 144A" means Rule 144A under the Securities Act, as such Rule may be
amended from time to time, or any similar rule or regulation hereafter adopted
by the SEC.

     "SEC" means the United States Securities and Exchange Commission.

     "Securities Act" means the Securities Act of 1933, as amended, and the
rules and regulations promulgated by the SEC thereunder.

     "Shelf Registration Statement" has the meaning set forth in Section 2(a)
hereof.

     "Subsequent Shelf Registration Statement" has the meaning set forth in
Section 2(b) hereof.

     "TIA" means the Trust Indenture Act of 1939, as amended.

     "Trustee" means Wells Fargo Bank, National Association, the Trustee under
the Indenture.

     "Underlying Common Shares" means the Common Shares into which the Notes are
convertible or issued upon any such conversion.

     Section 2. Shelf Registration. (a) The Company shall prepare and file or
cause to be prepared and filed with the SEC, as soon as practicable but in any


                                       5
<PAGE>

event by the date (the "Filing Deadline Date") that is ninety (90) days after
the Issue Date, a Registration Statement for an offering to be made on a delayed
or continuous basis pursuant to Rule 415 of the Securities Act (a "Shelf
Registration Statement") registering the resale from time to time by Holders
thereof of all of the Registrable Securities (the "Initial Shelf Registration
Statement"). The Initial Shelf Registration Statement shall be on Form S-3 or
another appropriate form permitting registration of such Registrable Securities
for resale by such Holders in accordance with the reasonable methods of
distribution elected by the Holders, approved by the Company, and set forth in
the Initial Shelf Registration Statement. The Company shall use its commercially
reasonable efforts to cause the Initial Shelf Registration Statement to be
declared effective under the Securities Act as promptly as is practicable but in
any event by the date (the "Effectiveness Deadline Date") that is two hundred
ten (210) days after the Issue Date, and to keep the Initial Shelf Registration
Statement (or any Subsequent Shelf Registration Statement) continuously
effective under the Securities Act until the expiration of the Effectiveness
Period. At the time the Initial Shelf Registration Statement is declared
effective, each Holder that became a Notice Holder on or prior to the date that
is five (5) Business Days prior to such time of effectiveness shall be named as
a selling securityholder in the Initial Shelf Registration Statement and the
related Prospectus in such a manner as to permit such Holder to deliver such
Prospectus to purchasers of Registrable Securities in accordance with applicable
law.

     (b) If the Initial Shelf Registration Statement or any Subsequent Shelf
Registration Statement ceases to be effective for any reason at any time during
the Effectiveness Period, the Company shall use its commercially reasonable
efforts to obtain the prompt withdrawal of any order suspending the
effectiveness thereof, and in any event shall within five (5) Business Days of
such cessation of effectiveness amend the Shelf Registration Statement in a
manner reasonably expected to obtain the withdrawal of the order suspending the
effectiveness thereof, or file an additional Shelf Registration Statement
covering all of the securities that as of the date of such filing are
Registrable Securities (a "Subsequent Shelf Registration Statement"). If a
Subsequent Shelf Registration Statement is filed, the Company shall use its
commercially reasonable efforts to cause the Subsequent Shelf Registration
Statement to become effective as promptly as is practicable after such filing
and to keep such Registration Statement (or subsequent Shelf Registration
Statement) continuously effective until the end of the Effectiveness Period.

     (c) The Company shall supplement and amend the Shelf Registration Statement
if required by the rules, regulations or instructions applicable to the
registration form used by the Company for such Shelf Registration Statement, if
required by the Securities Act or as reasonably requested by the Initial
Purchasers or by the Trustee on behalf of the Holders of the Registrable
Securities covered by such Shelf Registration Statement.



                                       6
<PAGE>

     (d) Each Holder of Registrable Securities agrees that if such Holder wishes
to sell Registrable Securities pursuant to a Shelf Registration Statement and
related Prospectus, it will do so only in accordance with this Section 2(d) and
Section 3(i). Each Holder of Registrable Securities wishing to sell Registrable
Securities pursuant to a Shelf Registration Statement and related Prospectus
agrees to deliver a Notice and Questionnaire to the Company at least three (3)
Business Days prior to any intended distribution of Registrable Securities under
the Shelf Registration Statement; provided that Holders of Registrable
Securities shall have at least twenty (20) Business Days from the date on which
the Notice and Questionnaire is first received by such Holders to return a
completed and signed Notice and Questionnaire to the Company. From and after the
date the Initial Shelf Registration Statement is declared effective, the Company
shall, as promptly as practicable after the date a Notice and Questionnaire is
delivered, and in any event within the later of (x) five (5) Business Days after
such date or (y) five (5) Business Days after the expiration of any Deferral
Period in effect when the Notice and Questionnaire is delivered or put into
effect within five (5) Business Days of such delivery date, (i) if required by
applicable law, file with the SEC a post-effective amendment to the Shelf
Registration Statement or, if required by applicable law, prepare and file a
supplement to the related Prospectus or a supplement or amendment to any
document incorporated therein by reference or file any other required document
so that the Holder delivering such Notice and Questionnaire is named as a
selling securityholder in the Shelf Registration Statement and the related
Prospectus in such a manner as to permit such Holder to deliver such Prospectus
to purchasers of the Registrable Securities in accordance with applicable law
and, if the Company shall file a post-effective amendment to the Shelf
Registration Statement, use its commercially reasonable efforts to cause such
post-effective amendment to be declared effective under the Securities Act as
promptly as is practicable, but in any event by the date (the "Amendment
Effectiveness Deadline Date") that is thirty (30) days after the date such
post-effective amendment is required by this clause to be filed; (ii) provide
such Holder copies of any documents filed pursuant to Section 2(d)(i); and (iii)
notify such Holder as promptly as practicable after the effectiveness under the
Securities Act of any post-effective amendment filed pursuant to Section
2(d)(i); provided that if such Notice and Questionnaire is delivered during a
Deferral Period, or a Deferral Period is put into effect within five (5)
Business Days after such delivery date, the Company shall so inform the Holder
delivering such Notice and Questionnaire and shall take the actions set forth in
clauses (i), (ii) and (iii) above within five (5) Business Days after expiration
of the Deferral Period in accordance with Section 3(i); provided further that if
under applicable law, the Company has more than one option as to the type or
manner of making any such filing, the Company will make the required filing or
filings in the manner or of a type that is reasonably expected to result in the
earliest availability of the Prospectus for effecting resales of Registrable
Securities; provided further that in no event will the Company be required to
file with the SEC (x) a supplement to the Prospectus more than once in any
calendar month, or (y) a post-effective amendment to the Shelf Registration
Statement more than once in any



                                       7
<PAGE>

calendar quarter, in each case solely for the purpose of naming any Holder, who
is not included in the Shelf Registration Statement, as a selling securityholder
in the Shelf Registration Statement and the related Prospectus. Notwithstanding
anything contained herein to the contrary, the Company shall be under no
obligation to name any Holder that is not a Notice Holder as a selling
securityholder in any Registration Statement or related Prospectus; provided,
however, that any Holder that becomes a Notice Holder pursuant to the provisions
of this Section 2(d) (whether or not such Holder was a Notice Holder at the time
the Registration Statement was declared effective) shall be named as a selling
securityholder in the Registration Statement or related Prospectus in accordance
with the requirements of this Section 2(d).

     (e) The parties hereto agree that the Holders of Registrable Securities
will suffer damages, and that it would not be feasible to ascertain the extent
of such damages with precision, if (i) the Initial Shelf Registration Statement
has not been filed on or prior to the Filing Deadline Date, (ii) the Initial
Shelf Registration Statement has not been declared effective under the
Securities Act on or prior to the Effectiveness Deadline Date, (iii) the Company
has failed to perform its obligations set forth in Section 2(b) within the time
period required therein, (iv) the Company has failed to perform its obligations
set forth in Section 2(d) within the time periods required therein or (v) the
aggregate duration of Deferral Periods in any period exceeds the number of days
permitted in respect of such period pursuant to Section 3(i) hereof (each of the
events of a type described in any of the foregoing clauses (i) through (v) are
individually referred to herein as an "Event," and the Filing Deadline Date in
the case of clause (i), the Effectiveness Deadline Date in the case of clause
(ii), the date by which the Company is required to perform its obligations set
forth in Section 2(b) in the case of clause (iii), the date by which the Company
is required to perform its obligations set forth in Section 2(d) in the case of
clause (iv) (including the filing of any post-effective amendment prior to the
Amendment Effectiveness Deadline Date), and the date on which the aggregate
duration of Deferral Periods in any period exceeds the number of days permitted
by Section 3(i) hereof in the case of clause (v), being referred to herein as an
"Event Date"). Events shall be deemed to continue until the following dates with
respect to the respective types of Events: the date the Initial Shelf
Registration Statement is filed in the case of an Event of the type described in
clause (i), the date the Initial Shelf Registration Statement is declared
effective under the Securities Act in the case of an Event of the type described
in clause (ii), the date the Company performs its obligations set forth in
Section 2(b) in the case of an Event of the type described in clause (iii), the
date the Company performs its obligations set forth in Section 2(d) in the case
of an Event of the type described in clause (iv) (including, without limitation,
the date the relevant post-effective amendment to the Shelf Registration
Statement is declared effective under the Securities Act), and termination of
the Deferral Period that caused the limit on the aggregate duration of Deferral
Periods in a period set forth in Section 3(i) to be exceeded in the case of the
commencement of an Event of the type described in clause (v).



                                       8
<PAGE>

     Accordingly, commencing on (and including) any Event Date and ending on
(but excluding) the next date on which there are no Events that have occurred
and are continuing (a "Damages Accrual Period"), the Company agrees to pay, as
liquidated damages and not as a penalty, an amount (the "Liquidated Damages
Amount"), payable on the Damages Payment Dates to Record Holders of Notes that
are Registrable Securities and of shares of Underlying Common Shares issued upon
conversion of Notes that are Registrable Securities, as the case may be,
accruing, for each portion of such Damages Accrual Period beginning on and
including a Damages Payment Date (or, if the first date of any Damages Accrual
Period for which the Liquidated Damages Amount is to be paid to Holders as a
result of the occurrence of any particular Event is other than a Damages Payment
Date, then the Event Date) and ending on but excluding the first to occur of (A)
the date of the end of the Damages Accrual Period or (B) the next Damages
Payment Date, at a rate per annum equal to one-quarter of one percent (0.25%)
for the first 90-day period from the Event Date, and thereafter at a rate per
annum equal to one-half of one percent (0.5%) of (i) the aggregate principal
amount of such Notes or, without duplication, (ii) in the case of Notes that
have been converted into or exchanged for Underlying Common Shares, the
Applicable Conversion Price of such shares of Underlying Common Shares on the
date of conversion, as the case may be, in each case determined as of the
Business Day immediately preceding the next Damages Payment Date; provided that
in the case of a Damages Accrual Period that is in effect solely as a result of
an Event of the type described in clause (iv) of the immediately preceding
paragraph, such Liquidated Damages Amount shall be paid only to the Holders that
have delivered Notice and Questionnaires that caused the Company to incur the
obligations set forth in Section 2(d), the non-performance of which is the basis
of such Event; provided further that any Liquidated Damages Amount accrued with
respect to any Note or portion thereof converted into Underlying Common Shares
on a conversion date prior to the Damages Payment Date, shall, in any such
event, be paid instead to the Holder who submitted such Note or portion thereof
for conversion on the applicable conversion date. Notwithstanding the foregoing,
no Liquidated Damages Amounts shall accrue as to any Registrable Security from
and after the earlier of (x) the date such security is no longer a Registrable
Security and (y) expiration of the Effectiveness Period. The rate of accrual of
the Liquidated Damages Amount with respect to any period shall not exceed the
rate provided for in this paragraph notwithstanding the occurrence of multiple
concurrent Events. Following the cure of all Events requiring the payment by the
Company of Liquidated Damages Amounts to the Holders of Registrable Securities
pursuant to this Section, the accrual of Liquidated Damages Amounts will cease
(without in any way limiting the effect of any subsequent Event requiring the
payment of Liquidated Damages Amount by the Company).

     The Trustee shall be entitled, on behalf of Holders of Notes, to seek any
available remedy for the enforcement of this Agreement, including for the
payment of any Liquidated Damages Amount. Notwithstanding the foregoing, the
parties agree that the sole damages payable for a violation of the terms of this


                                       9
<PAGE>

Agreement with respect to which liquidated damages are expressly provided shall
be such liquidated damages.

     All of the Company's obligations set forth in this Section 2(e) that are
outstanding with respect to any Registrable Security at the time such security
ceases to be a Registrable Security shall survive until such time as all such
obligations with respect to such security have been satisfied in full
(notwithstanding termination of this Agreement pursuant to Section 8(k)).

     The parties hereto agree that the liquidated damages provided for in this
Section 2(e) constitute a reasonable estimate of the damages that may be
incurred by Holders of Registrable Securities by reason of the failure of the
Shelf Registration Statement to be filed or declared effective or available for
effecting resales of Registrable Securities in accordance with the provisions
hereof.

     Section 3. Registration Procedures. In connection with the registration
obligations of the Company under Section 2 hereof, the Company shall:

     (a) Prepare and file with the SEC a Registration Statement or Registration
Statements on any appropriate form under the Securities Act available for the
sale of the Registrable Securities by the Holders thereof in accordance with the
intended method or methods of distribution thereof, and use its commercially
reasonable efforts to cause each such Registration Statement to become effective
and remain effective as provided herein; provided that before filing any
Registration Statement or Prospectus or any amendments or supplements thereto
with the SEC, the Company shall furnish to the Initial Purchasers and counsel
for the Holders and for the Initial Purchasers (or, if applicable, one separate
counsel for the Holders) copies of all such documents proposed to be filed and
use its commercially reasonable efforts to reflect in each such document when so
filed with the SEC such comments as such counsel reasonably shall propose within
three (3) Business Days of the delivery of such copies to the Initial Purchasers
and such counsel.

     (b) Prepare and file with the SEC such amendments and post-effective
amendments to each Registration Statement as may be necessary to keep such
Registration Statement continuously effective until the expiration of the
Effectiveness Period; cause the related Prospectus to be supplemented by any
required Prospectus supplement, and as so supplemented to be filed pursuant to
Rule 424 (or any similar provisions then in force) under the Securities Act; and
use its commercially reasonable efforts to comply with the provisions of the
Securities Act applicable to them with respect to the disposition of all
securities covered by such Registration Statement during the Effectiveness
Period in accordance with the intended methods of disposition by the sellers
thereof set forth in such Registration Statement as so amended or such
Prospectus as so supplemented.



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<PAGE>

     (c) As promptly as practicable give notice to the Initial Purchasers, the
Holders and counsel for the Holders and for the Initial Purchasers (or, if
applicable, one separate counsel for the Holders) (i) when any Prospectus,
Prospectus supplement, Registration Statement or post-effective amendment to a
Registration Statement has been filed with the SEC and, with respect to a
Registration Statement or any post-effective amendment, when the same has been
declared effective, (ii) of any request, following the effectiveness of the
Initial Shelf Registration Statement under the Securities Act, by the SEC or any
other federal or state governmental authority for amendments or supplements to
any Registration Statement or related Prospectus or for additional information,
(iii) of the issuance by the SEC or any other federal or state governmental
authority of any stop order suspending the effectiveness of any Registration
Statement or the initiation or threatening of any proceedings for that purpose,
(iv) of the receipt by the Company of any notification with respect to the
suspension of the qualification or exemption from qualification of any of the
Registrable Securities for sale in any jurisdiction or the initiation or
threatening of any proceeding for such purpose, (v) after the effective date of
any Registration Statement filed pursuant to this Agreement of the occurrence of
(but not the nature of or details concerning) a Material Event and (vi) of the
determination by the Company that a post-effective amendment to a Registration
Statement will be filed with the SEC, which notice may, at the discretion of the
Company (or as required pursuant to Section 3(i)), state that it constitutes a
Deferral Notice, in which event the provisions of Section 3(i) shall apply.

     (d) Use its commercially reasonable efforts to prevent the issuance of,
and, if issued, to obtain the withdrawal of any order suspending the
effectiveness of a Registration Statement or the lifting of any suspension of
the qualification (or exemption from qualification) of any of the Registrable
Securities for sale in any jurisdiction in which they have been qualified for
sale, in either case at the earliest possible moment, and provide prompt notice
to each Notice Holder and the Initial Purchasers of the withdrawal of any such
order.

     (e) If reasonably requested by the Initial Purchasers or any Notice Holder,
as promptly as practicable incorporate in a Prospectus supplement or
post-effective amendment to a Registration Statement such information as the
Initial Purchasers, such Notice Holder or counsel for the Holders and for the
Initial Purchasers (or, if applicable, one separate counsel for the Holders)
shall, on the basis of a written opinion of nationally-recognized counsel
experienced in such matters, determine to be required to be included therein by
applicable law and make any required filings of such Prospectus supplement or
such post-effective amendment provided that the Company shall not be required to
take any actions under this Section 3(e) that, in the written opinion of counsel
for the Company, are not in compliance with applicable law.

     (f) As promptly as practicable furnish to each Notice Holder, counsel for
the Holders and for the Initial Purchasers (or, if applicable, one separate
counsel for the Holders) and the Initial Purchasers, without charge, at least
one (1)



                                       11
<PAGE>

conformed copy of the Registration Statement and any amendment thereto,
including financial statements but excluding schedules, all documents
incorporated or deemed to be incorporated therein by reference and all exhibits
(unless requested in writing to the Company by such Notice Holder, such counsel
or the Initial Purchasers).

     (g) During the Effectiveness Period, deliver to each Notice Holder, counsel
for the Holders and for the Initial Purchasers (or, if applicable, one separate
counsel for the Holders) and the Initial Purchasers, in connection with any sale
of Registrable Securities pursuant to a Registration Statement, without charge,
as many copies of the Prospectus or Prospectuses relating to such Registrable
Securities (including each preliminary prospectus) and any amendment or
supplement thereto as may reasonably be requested; and the Company hereby
consents (except during such periods that a Deferral Notice is outstanding and
has not been revoked) to the use of such Prospectus and each amendment or
supplement thereto by each Notice Holder, in connection with any offering and
sale of the Registrable Securities covered by such Prospectus or any amendment
or supplement thereto in the manner set forth therein.

     (h) Prior to any public offering of the Registrable Securities pursuant to
the Shelf Registration Statement, use its commercially reasonable efforts to
register or qualify or cooperate with the Notice Holders in connection with the
registration or qualification (or exemption from such registration or
qualification) of such Registrable Securities for offer and sale under the
securities or Blue Sky laws of such jurisdictions within the United States as
any Notice Holder reasonably requests in writing (which request may be included
in the Notice and Questionnaire); prior to any public offering of the
Registrable Securities pursuant to the Shelf Registration Statement, use its
commercially reasonable efforts to keep each such registration or qualification
(or exemption therefrom) effective during the Effectiveness Period in connection
with such Notice Holder's offer and sale of Registrable Securities pursuant to
such registration or qualification (or exemption therefrom) and do any and all
other acts or things reasonably necessary or advisable to enable the disposition
in such jurisdictions of such Registrable Securities in the manner set forth in
the relevant Registration Statement and the related Prospectus; provided that
the Company will not be required to (i) qualify as a foreign corporation or as a
dealer in securities in any jurisdiction where they would not otherwise be
required to qualify but for this Agreement or (ii) take any action that would
subject them to general service of process in suits or to taxation in any such
jurisdiction where they are not then so subject.

     (i) Upon (A) the issuance by the SEC of a stop order suspending the
effectiveness of the Shelf Registration Statement or the initiation of
proceedings with respect to the Shelf Registration Statement under Section 8(d)
or 8(e) of the Securities Act, (B) the occurrence of any event or the existence
of any fact as a result of which any Registration Statement shall contain any
untrue statement of a material fact or omit to state any material fact required
to be stated therein or necessary to make the statements therein not misleading,
or any Prospectus shall



                                       12
<PAGE>

contain any untrue statement of a material fact or omit to state any material
fact necessary in order to make the statements therein, in the light of the
circumstances under which they were made, not misleading, or (C) the occurrence
or existence of any pending corporate development (a "Material Event") that, in
the reasonable discretion of the Company, makes it appropriate to suspend the
availability of the Shelf Registration Statement and the related Prospectus, (i)
in the case of clause (B) above, subject to the next sentence, as promptly as
practicable prepare and file, if necessary pursuant to applicable law, a
post-effective amendment to such Registration Statement or a supplement to the
related Prospectus or any document incorporated therein by reference or file any
other required document that would be incorporated by reference into such
Registration Statement and Prospectus so that such Registration Statement does
not contain any untrue statement of a material fact or omit to state any
material fact required to be stated therein or necessary to make the statements
therein not misleading, and such Prospectus does not contain any untrue
statement of a material fact or omit to state any material fact necessary in
order to make the statements therein, in the light of the circumstances under
which they were made, not misleading (it being understood that the Company may
rely on information provided by each Notice Holder with respect to such Notice
Holder), as thereafter delivered to the purchasers of the Registrable Securities
being sold thereunder, and, in the case of a post-effective amendment to a
Registration Statement, subject to the next sentence, use its commercially
reasonable efforts to cause it to be declared effective as promptly as is
practicable, and (ii) give notice to the Notice Holders, the Initial Purchasers
and counsel for the Holders and for the Initial Purchasers (or, if applicable,
one separate counsel for the Holders) that the availability of the Shelf
Registration Statement is suspended (a "Deferral Notice") and, upon receipt of
any Deferral Notice, each Notice Holder agrees not to sell any Registrable
Securities pursuant to the Registration Statement until such Notice Holder's
receipt of copies of the supplemented or amended Prospectus provided for in
clause (i) above, or until it is advised in writing by the Company that the
Prospectus may be used, and has received copies of any additional or
supplemental filings that are incorporated or deemed incorporated by reference
in such Prospectus. The Company will use its commercially reasonable efforts to
ensure that the use of the Prospectus may be resumed (x) in the case of clause
(A) above, as promptly as is practicable, (y) in the case of clause (B) above,
as soon as, in the reasonable judgment of the Company, the Registration
Statement does not contain any untrue statement of a material fact or omits to
state any material fact required to be stated therein or necessary to make the
statements therein not misleading and the Prospectus does not contain any untrue
statement of a material fact or omits to state any material fact necessary in
order to make the statements therein, in the light of the circumstances under
which they were made, not misleading, and (z) in the case of clause (C) above,
as soon as, in the reasonable discretion of the Company, such suspension is no
longer appropriate. The period during which the availability of the Registration
Statement and any Prospectus is suspended without the Company incurring any
obligation to pay Liquidated Damages Amount (the "Deferral Period"), shall not
exceed forty-five (45) days



                                       13
<PAGE>

in any ninety- (90-) day period and one hundred twenty (120) days in any twelve-
(12-) month period; provided, however, that in the case of clause (C) above, the
Deferral Period may be extended from forty-five (45) to sixty (60) days.

     (j) If reasonably requested in writing in connection with any disposition
of Registrable Securities pursuant to a Shelf Registration Statement, make
available for inspection during normal business hours by a representative for
the Notice Holders of such Registrable Securities, and any broker-dealers,
attorneys and accountants retained by such Notice Holders, all relevant
financial and other records and pertinent corporate documents and properties of
the Company and its subsidiaries, and cause the appropriate officers, directors
and employees of the Company and its subsidiaries to make available for
inspection during normal business hours all relevant information reasonably
requested by such representative for the Notice Holders, or any such
broker-dealers, attorneys or accountants in connection with such disposition, in
each case as is customary for similar "due diligence" examinations; provided,
however, that such persons shall first agree in writing with the Company that
any information that is in good faith designated by the Company in writing as
confidential at the time of delivery of such information shall be kept
confidential by such persons and shall be used solely for the purposes of
exercising rights under this Agreement, unless (i) disclosure of such
information is required by court or administrative order or is necessary to
respond to inquiries of regulatory authorities, (ii) disclosure of such
information is required by law (including any disclosure requirements pursuant
to federal securities laws in connection with the filing of any Registration
Statement or the use of any Prospectus referred to in this Agreement), (iii)
such information becomes generally available to the public other than as a
result of a disclosure or failure to safeguard by any such person or (iv) such
information becomes available to any such person from a source other than the
Company and such source is not bound by a confidentiality agreement or is not
otherwise under a duty of trust to the Company, and provided that the foregoing
inspection and information gathering shall, to the greatest extent possible, be
coordinated on behalf of all the Notice Holders and the other parties entitled
thereto by the one counsel for the Holders referred to in Section 5, provided
further, that the Company shall not be required to furnish any such documents
that are publicly available through the EDGAR electronic filing system of the
SEC.

     (k) Comply with all applicable rules and regulations of the SEC and make
generally available to its securityholders earning statements (which need not be
audited) satisfying the provisions of Section 11(a) of the Securities Act and
Rule 158 thereunder (or any similar rule promulgated under the Securities Act)
no later than 45 days after the end of any 12-month period (or 90 days after the
end of any 12-month period if such period is a fiscal year) commencing on the
first day of the first fiscal quarter of the Company commencing after the
effective date of a Registration Statement, which statements shall cover said
12-month periods.

     (l) Cooperate with each Notice Holder to facilitate the timely preparation
and delivery of certificates representing Registrable Securities sold



                                       14
<PAGE>

pursuant to a Registration Statement, which certificates shall not bear any
restrictive legends, and cause such Registrable Securities to be in such
denominations as are permitted by the Indenture and registered in such names as
such Notice Holder may request in writing at least (2) Business Days prior to
any sale of such Registrable Securities.

     (m) Provide a CUSIP number for all Registrable Securities covered by each
Registration Statement not later than the effective date of such Registration
Statement and provide the Trustee and the transfer agent for the Common Shares
with printed certificates for the Registrable Securities that are in a form
eligible for deposit with The Depository Trust Company.

     (n) Cooperate and assist in any filings required to be made with the
National Association of Securities Dealers, Inc.

     (o) Enter into such customary agreements and take all such other reasonably
requested actions in connection therewith (including those requested by the
holders of a majority of the Registrable Securities being sold) in order to
expedite or facilitate disposition of such Registrable Securities.

     (p) Cause the Indenture to be qualified under the TIA not later than the
effective date of any Registration Statement; and in connection therewith,
cooperate with the Trustee to effect such changes to the Indenture as may be
required for the Indenture to be so qualified in accordance with the terms of
the TIA and execute, and use its commercially reasonable efforts to cause the
Trustee to execute, all documents as may be required to effect such changes, and
all other forms and documents required to be filed with the SEC to enable the
Indenture to be so qualified in a timely manner.

     Section 4. Holder's Obligations. Each Holder agrees, by acquisition of the
Registrable Securities, that no Holder of Registrable Securities shall be
entitled to sell any of such Registrable Securities pursuant to a Registration
Statement or to receive a Prospectus relating thereto, unless such Holder has
furnished the Company with a Notice and Questionnaire as required pursuant to
Section 2(d) hereof (including the information required to be included in such
Notice and Questionnaire) and the information set forth in the next sentence.
Each Notice Holder agrees promptly to furnish to the Company all information
required to be disclosed in order to make the information previously furnished
to the Company by such Notice Holder not misleading and any other information
regarding such Notice Holder and the distribution of such Registrable Securities
as the Company may from time to time reasonably request. Any sale of any
Registrable Securities by any Holder shall constitute a representation and
warranty by such Holder that the information relating to such Holder and its
plan of distribution is as set forth in the Prospectus delivered by such Holder
in connection with such disposition, that such Prospectus does not as of the


                                       15
<PAGE>

time of such sale contain any untrue statement of a material fact relating to or
provided by such Holder or its plan of distribution and that such Prospectus
does not as of the time of such sale omit to state any material fact relating to
or provided by such Holder or its plan of distribution necessary in order to
make the statements in such Prospectus, in the light of the circumstances under
which they were made, not misleading.

     Section 5. Registration Expenses. The Company shall bear all fees and
expenses incurred in connection with the performance by the Company of its
obligations under Sections 2 and 3 of this Agreement whether or not any of the
Registration Statements are declared effective. Such fees and expenses
("Registration Expenses") shall include, without limitation, (i) all
registration and filing fees (including, without limitation, fees and expenses
(x) with respect to filings required to be made with the National Association of
Securities Dealers, Inc. and (y) of compliance with federal and state securities
or Blue Sky laws (including, without limitation, reasonable fees and
disbursements of counsel for the Holders in connection with Blue Sky
qualifications of the Registrable Securities under the laws of such
jurisdictions as the Notice Holders of a majority of the Registrable Securities
being sold pursuant to a Registration Statement may designate), (ii) printing
expenses (including, without limitation, expenses of printing certificates for
Registrable Securities in a form eligible for deposit with The Depository Trust
Company), (iii) duplication expenses relating to copies of any Registration
Statement or Prospectus delivered to any Holders hereunder, (iv) fees and
disbursements of counsel for the Company and the fees and disbursements of one
counsel for the Holders in connection with the Shelf Registration Statement, (v)
fees and disbursements of the Trustee and its counsel and of the registrar and
transfer agent for the Common Shares and (vi) Securities Act liability insurance
obtained by the Company in its sole discretion. In addition, the Company shall
pay the internal expenses of the Company (including, without limitation, all
salaries and expenses of officers and employees performing legal or accounting
duties), the expense of any annual audit, the fees and expenses incurred in
connection with the listing by the Company of the Registrable Securities on any
securities exchange on which similar securities of the Company are then listed
and the fees and expenses of any person, including special experts, retained by
the Company.

     Section 6. Indemnification; Contribution.

     (a) The Company agrees to indemnify and hold harmless the Initial
Purchasers, each Holder and each person, if any, who controls any Initial
Purchaser or any Holder within the meaning of Section 15 of the 1933 Act or
Section 20 of the 1934 Act as follows:

          (i) against any and all loss, liability, claim, damage and expense
     whatsoever, as incurred, arising out of any untrue statement or alleged
     untrue statement of a material fact contained in any Registration Statement
     (or any amendment or supplement thereto) pursuant to which Registrable
     Securities were registered under the 1933 Act, including all documents
     incorporated therein by reference, or the omission or alleged



                                       16
<PAGE>

     omission therefrom of a material fact required to be stated therein or
     necessary to make the statements therein not misleading, or arising out of
     any untrue statement or alleged untrue statement of a material fact
     contained in any Prospectus (or any amendment or supplement thereto) or the
     omission or alleged omission therefrom of a material fact necessary in
     order to make the statements therein, in the light of the circumstances
     under which they were made, not misleading;

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

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

provided, however, that this indemnity agreement shall not apply to any loss,
liability, claim, damage or expense to the extent arising out of any untrue
statement or omission or alleged untrue statement or omission made in reliance
upon and in conformity with written information furnished to the Company by the
Initial Purchasers or such Holder expressly for use in a Registration Statement
(or any amendment thereto) or any Prospectus (or any amendment or supplement
thereto).

     (b) Each Holder severally, but not jointly, agrees to indemnify and hold
harmless the Company, the Initial Purchasers, the other selling Holders, and
each of their respective directors and officers, and each person, if any, who
controls the Company, any Initial Purchaser or any other selling Holder within
the meaning of Section 15 of the 1933 Act or Section 20 of the 1934 Act, against
any and all loss, liability, claim, damage and expense described in the
indemnity contained in Section 6(a) hereof, as incurred, but only with respect
to untrue statements or omissions, or alleged untrue statements or omissions,
made in the Shelf Registration Statement (or any amendment thereto) or any
Prospectus included therein (or any amendment or supplement



                                       17
<PAGE>

thereto) in reliance upon and in conformity with written information with
respect to such Holder furnished to the Company by such Holder expressly for use
in the Shelf Registration Statement (or any amendment thereto) or such
Prospectus (or any amendment or supplement thereto); provided, however, that no
such Holder shall be liable for any claims hereunder in excess of the amount of
net proceeds received by such Holder from the sale of Registrable Securities
pursuant to such Shelf Registration Statement.

     (c) Each indemnified party shall give notice as promptly as reasonably
practicable to each indemnifying party of any action or proceeding commenced
against it in respect of which indemnity may be sought hereunder, but failure so
to notify an indemnifying party shall not relieve such indemnifying party from
any liability hereunder to the extent it is not materially prejudiced as a
result thereof and in any event shall not relieve it from any liability which it
may have otherwise than on account of this Section 6. An indemnifying party,
upon request of the indemnified party, shall retain counsel reasonably
satisfactory to the indemnified party to represent the indemnified party and
others the indemnifying party may designate in such proceeding and shall pay the
fees and expenses of such counsel related to such proceeding; provided, however,
that counsel to the indemnifying party shall not (except with the consent of the
indemnified party) also be counsel to the indemnified party. In no event shall
the indemnifying party or parties be liable for the fees and expenses of more
than one counsel (in addition to any local counsel) separate from their own
counsel for all indemnified parties in connection with any one action or
separate but similar or related actions in the same jurisdiction arising out of
the same general allegations or circumstances. No indemnifying party shall,
without the prior written consent of the indemnified parties, settle or
compromise or consent to the entry of any judgment with respect to any
litigation, or any investigation or proceeding by any governmental agency or
body, commenced or threatened, or any claim whatsoever in respect of which
indemnification or contribution could be sought under this Section 6 (whether or
not the indemnified parties are actual or potential parties thereto), unless
such settlement, compromise or consent (i) includes an unconditional release of
each indemnified party from all liability arising out of such litigation,
investigation, proceeding or claim and (ii) does not include a statement as to
or an admission of fault, culpability or a failure to act by or on behalf of any
indemnified party.

     (d) If at any time an indemnified party shall have requested an
indemnifying party to reimburse the indemnified party for fees and expenses of
counsel, such indemnifying party agrees that it shall be liable for any
settlement of the nature contemplated by Section 6(a)(ii) effected without its
written consent if (i) such settlement is entered into more than 45 days after
receipt by such indemnifying party of the aforesaid request, (ii) such
indemnifying party shall have received notice of the terms of such settlement at
least 45 days prior to such settlement being entered into and (iii) such
indemnifying party shall not have reimbursed such indemnified party in
accordance with such request prior to the date of such settlement.

     (e) If the indemnification provided for in this Section 6 is for any reason
unavailable to or insufficient to hold harmless an indemnified party in respect
of any losses, liabilities, claims, damages or expenses referred to therein,
then each indemnifying party shall contribute to the aggregate amount of such
losses,



                                       18
<PAGE>

liabilities, claims, damages and expenses incurred by such indemnified party, as
incurred, in such proportion as is appropriate to reflect the relative fault of
the indemnifying party or parties on the one hand and the indemnified party on
the other hand in connection with the statements or omissions that resulted in
such losses, liabilities, claims, damages or expenses, as well as any other
relevant equitable considerations.

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

     The Company and the Holders agree that it would not be just and equitable
if contribution pursuant to this Section 6(e) were determined by pro rata
allocation or by any other method of allocation that does not take account of
the equitable considerations referred to above in this Section 6(e). The
aggregate amount of losses, liabilities, claims, damages and expenses incurred
by an indemnified party and referred to above in this Section 6(e) shall be
deemed to include any legal or other expenses reasonably incurred by such
indemnified party in investigating, preparing or defending against any
litigation, or any investigation or proceeding by any governmental agency or
body, commenced or threatened, or any claim whatsoever based upon any such
untrue or alleged untrue statement or omission or alleged omission.

     Notwithstanding the provisions of this Section 6, no Holder shall be
required to indemnify or contribute any amount in excess of the amount by which
the total price at which the Registrable Securities sold by such Holder exceeds
the amount of any damages that such Holder has otherwise been required to pay by
reason of such untrue or alleged untrue statement or omission or alleged
omission.

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

     For purposes of this Section 6, each person, if any, who controls any
Initial Purchaser or any Holder within the meaning of Section 15 of the
Securities Act or Section 20 of the Exchange Act shall have the same rights to
contribution as such Initial Purchaser or Holder, and each director of and each
person, if any, who controls the Company within the meaning of Section 15 of the
Securities Act or Section 20 of the Exchange Act shall have the same rights to
contribution as the Company.

     Section 7. Information Requirements. (a) The Company covenants that, if at
any time before the end of the Effectiveness Period it is not subject to the
reporting requirements of the Exchange Act, it will cooperate with any Holder of


                                       19
<PAGE>

Registrable Securities and take such further reasonable action as any Holder of
Registrable Securities may reasonably request in writing (including, without
limitation, making such reasonable representations as any such Holder may
reasonably request), all to the extent required from time to time to enable such
Holder to sell Registrable Securities without registration under the Securities
Act within the limitation of the exemptions provided by Rule 144 and Rule 144A
under the Securities Act and customarily taken in connection with sales pursuant
to such exemptions. Upon the written request of any Holder of Registrable
Securities, the Company shall deliver to such Holder a written statement as to
whether it has complied with such filing requirements, unless such a statement
has been included in its most recent report filed pursuant to Section 13 or
Section 15(d) of Exchange Act. Notwithstanding the foregoing, nothing in this
Section 7 shall be deemed to require the Company to register any of its
securities (other than the Common Shares) under any section of the Exchange Act.

     (b) The Company shall file the reports required to be filed by it under the
Exchange Act and shall comply with all other requirements set forth in the
instructions to Form S-3 (or such other form as may be applicable) in order to
allow it to be eligible to file registration statements on Form S-3 (or such
other form as may be applicable).

     Section 8. Miscellaneous.

     (a) No Conflicting Agreements. The Company is not, as of the date hereof, a
party to, nor shall it, on or after the date of this Agreement, enter into, any
agreement with respect to its securities that conflicts with the rights granted
to the Holders of Registrable Securities in this Agreement. The Company
represents and warrants that the rights granted to the Holders of Registrable
Securities hereunder do not in any way conflict with the rights granted to the
holders of the Company's securities under any other agreements. Notwithstanding
the foregoing, the Initial Purchasers and the Holders acknowledge that the
Company is obligated, and may obligate itself from time to time in the future,
to register its securities for other holders pursuant to separate registration
statements.

     (b) Amendments and Waivers. The provisions of this Agreement, including the
provisions of this sentence, may not be amended, modified or supplemented, and
waivers or consents to departures from the provisions hereof may not be given,
unless the Company has obtained the written consent of Holders of a majority of
the then outstanding Underlying Common Shares constituting Registrable
Securities (with Holders of Notes deemed to be the Holders, for purposes of this
Section, of the number of outstanding shares of Underlying Common Shares into
which such Notes are or would be convertible or exchangeable as of the date on
which such consent is requested). Notwithstanding the foregoing, a waiver or
consent to depart from the provisions hereof with respect to a matter that
relates exclusively to the rights of Holders of Registrable Securities whose
securities are being sold pursuant to a Registration Statement and that does not
directly or indirectly affect the rights of other Holders of



                                       20
<PAGE>

Registrable Securities may be given by Holders of at least a majority of the
Underlying Common Shares constituting Registrable Securities being sold by such
Holders pursuant to such Registration Statement (with Holders of Notes deemed to
be the Holders, for purposes of this Section, of the number of outstanding
shares of Underlying Common Shares into which such Notes are or would be
convertible or exchangeable as of the date on which such consent is requested);
provided that the provisions of this sentence may not be amended, modified, or
supplemented except in accordance with the provisions of the immediately
preceding sentence. Each Holder of Registrable Securities outstanding at the
time of any such amendment, modification, supplement, waiver or consent or
thereafter shall be bound by any such amendment, modification, supplement,
waiver or consent effected pursuant to this Section 8(b), whether or not any
notice, writing or marking indicating such amendment, modification, supplement,
waiver or consent appears on the Registrable Securities or is delivered to such
Holder.

     (c) Notices. All notices and other communications provided for or permitted
hereunder shall be made in writing by hand delivery, by telecopier, by courier
guaranteeing overnight delivery or by first-class mail, return receipt
requested, and shall be deemed given (i) when made, if made by hand delivery,
(ii) upon confirmation, if made by telecopier, (iii) one (1) Business Day after
being deposited with such courier, if made by overnight courier or (iv) on the
date indicated on the notice of receipt, if made by first-class mail, to the
parties as follows:

     (x) if to a Holder of Registrable Securities, at the most current address
given by such Holder to the Company in a Notice and Questionnaire or any
amendment thereto;

     (y) if to the Company, to:

                XOMA Ltd.
                2910 Seventh Street
                Berkeley, California 94710
                Attention: Legal Department
                Telecopy No.: (510) 204-7200

                with a copy to (which shall not constitute notice):

                Cahill Gordon & Reindel LLP
                80 Pine Street, 17th Floor
                New York, NY 10005
                Attention:  Geoffrey E. Liebmann
                Telecopy No.: (212) 269-5420

         (z) if to the Initial Purchasers, to:



                                       21
<PAGE>

                J.P. Morgan Securities Inc.
                270 Park Avenue
                New York, NY 10017
                Attention: Syndicate Department
                Telecopy No.: (212) 622-2071

or to such other address as such person may have furnished to the other persons
identified in this Section 8(c) in writing in accordance herewith.

     (d) Approval of Holders. Whenever the consent or approval of Holders of a
specified percentage of Registrable Securities is required hereunder,
Registrable Securities held by the Company or its affiliates (as such term is
defined in Rule 405 under the Securities Act) (other than subsequent Holders of
Registrable Securities if such subsequent Holders are deemed to be such
affiliates solely by reason of their holdings of such Registrable Securities)
shall not be counted in determining whether such consent or approval was given
by the Holders of such required percentage.

     (e) Successors and Assigns. This Agreement shall inure to the benefit of
and be binding upon the successors and assigns of each of the parties and shall
inure to the benefit of and be binding upon each Holder of any Registrable
Securities, including, without the need for an express assignment or any consent
by the Company thereto, subsequent Holders of Registrable Securities.

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

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

     (h) Governing Law. THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK, WITHOUT REGARD TO CONFLICTS
OF LAWS PRINCIPLES THEREOF.

     (i) Severability. If any term, provision, covenant or restriction of this
Agreement is held to be invalid, illegal, void or unenforceable, the remainder
of the terms, provisions, covenants and restrictions set forth herein shall
remain in full force and effect and shall in no way be affected, impaired or
invalidated thereby, and the parties hereto shall use their commercially
reasonable efforts to find and employ an alternative means to achieve the same
or substantially the same result as that contemplated by such term, provision,
covenant or restriction, it being intended that all of the rights and privileges
of the parties shall be enforceable to the fullest extent permitted by law.



                                       22
<PAGE>

     (j) Entire Agreement. This Agreement is intended by the parties as a final
expression of their agreement and is intended to be a complete and exclusive
statement of the agreement and understanding of the parties hereto in respect of
the subject matter contained herein and the registration rights granted by the
Company with respect to the Registrable Securities. Except as provided in the
Purchase Agreement, there are no restrictions, promises, warranties or
undertakings, other than those set forth or referred to herein, with respect to
the registration rights granted by the Company with respect to the Registrable
Securities. This Agreement supersedes all prior agreements and undertakings
among the parties with respect to such registration rights. No party hereto
shall have any rights, duties or obligations other than those specifically set
forth in this Agreement. In no event will such methods of distribution take the
form of an underwritten offering of the Registrable Securities without the prior
agreement of the Company.

     (k) Termination. This Agreement and the obligations of the parties
hereunder shall terminate upon the end of the Effectiveness Period, except for
any liabilities or obligations under Section 5 or 6 hereof and the obligations
to make payments of and provide for liquidated damages under Section 2(e) hereof
to the extent such damages accrue prior to the end of the Effectiveness Period,
each of which shall remain in effect in accordance with its terms.




                                       23
<PAGE>



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

                             XOMA LTD.

                             By:
                                  --------------------------------------------
                                  Name:    Peter B. Davis
                                  Title:   Vice President, Finance and Chief
                                           Financial Officer






Confirmed and accepted as of the date first above written:

J.P. MORGAN SECURITIES INC.
ADAMS HARKNESS, INC
DEUTSCHE BANK SECURITIES, INC.
FIRST ALBANY CAPITAL, INC.
JEFFERIES & COMPANY, INC.

By: J.P. MORGAN SECURITIES INC.


    --------------------------------------------------
    Name:
    Title:





                                       24