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                                                                     EXHIBIT 4.7

                         REGISTRATION RIGHTS AGREEMENT

            This Registration Rights Agreement (this "Agreement") is made and
entered into as of April 5, 2002, by and among Hyseq, Inc., a Nevada corporation
(the "Company"), and the investors signatory hereto (each a "Purchaser" and
collectively, the "Purchasers").

            This Agreement is made pursuant to the Securities Purchase
Agreement, dated as of the date hereof among the Company and the Purchasers (the
"Purchase Agreement").

            The Company and the Purchasers hereby agree as follows:

            1. Definitions. Capitalized terms used and not otherwise defined
herein that are defined in the Purchase Agreement shall have the meanings given
such terms in the Purchase Agreement. As used in this Agreement, the following
terms shall have the following meanings:

            "Effectiveness Date" means, with respect to the initial Registration
Statement required to be filed hereunder, the earlier of (a) (i) the 90th day
following the Closing Date or (ii) the 45th day following the date that the
Company receives its first response (written or oral) from the Commission as to
the Company's first request for confidential treatment with respect to any
exhibits filed pursuant to confidential treatment requests prior to the date the
Registration Statement is filed with the Commission (regardless of whether such
response of the Commission is a request for additional information), whichever
is later and (b) the fifth Trading Day following the date on which the Company
is notified by the Commission that such Registration Statement will not be
reviewed or is no longer subject to further review and comments, and, with
respect to any additional Registration Statements that may be required pursuant
to Section 2(c), the earlier of (a) (i) the 90th day following the date on which
the Company first knows, or reasonably should have known, that such additional
Registration Statement is required under such Section or (ii) the 45th day
following the date that the Company receives its first response (written or
oral) from the Commission as to the Company's first request for confidential
treatment with respect to any exhibits filed pursuant to confidential treatment
requests prior to the date such additional Registration Statements is filed with
the Commission (regardless of whether such response of the Commission is a
request for additional information), whichever is later and (b) the fifth
Trading Day following the date on which the Company is notified by the
Commission that such Registration Statement will not be reviewed or is no longer
subject to further review and comments.

            "Effectiveness Period" shall have the meaning set forth in Section
2(a).

            "Filing Date" means, with respect to the initial Registration
Statement required to be filed hereunder, the 30th day following the Closing
Date, and, with respect to any additional Registration Statements that may be
required pursuant to Section 2(c), the 30th day following the date on which the
Company first knows, or reasonably should have known that such additional
Registration Statement is required under such Section.

            "Holder" or "Holders" means the holder or holders, as the case may
be, from time to time of Registrable Securities.


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            "Indemnified Party" shall have the meaning set forth in Section
5(c).

            "Indemnifying Party" shall have the meaning set forth in Section
5(c).

            "Losses" shall have the meaning set forth in Section 5(a).

            "Materially Detrimental" means, in the good faith judgment of the
Board of Directors of the Company as set forth in a certificate signed by the
President, Chief Financial Officer or General Counsel of the Company, the filing
in question would be materially detrimental to the Company by reason of (i) any
proceeding before, or material event involving, the Food and Drug
Administration, or (ii) any proposal or plan of the Company or any of its
Subsidiaries to engage in any sale, acquisition, merger, consolidation,
reorganization, tender offer or similar transaction.

            "Proceeding" means an action, claim, suit, investigation or
proceeding (including, without limitation, an investigation or partial
proceeding, such as a deposition), whether commenced or threatened.

            "Prospectus" means the prospectus included in a Registration
Statement (including, without limitation, a prospectus that includes any
information previously omitted from a prospectus filed as part of an effective
registration statement in reliance upon Rule 430A promulgated under the
Securities Act), as amended or supplemented by any prospectus supplement, with
respect to the terms of the offering of any portion of the Registrable
Securities covered by a Registration Statement, and all other amendments and
supplements to the Prospectus, including post-effective amendments, and all
material incorporated by reference or deemed to be incorporated by reference in
such Prospectus.

            "Registrable Securities" means (i) the Shares and (ii) the Warrant
Shares, together with any securities issued or issuable upon any stock split,
dividend or other distribution, recapitalization or similar event with respect
to the foregoing.

            "Registration Statement" means the initial registration statement
required to be filed hereunder and any additional registration statements
contemplated by Section 2(c), including (in each case) the Prospectus,
amendments and supplements to such registration statement or Prospectus,
including pre- and post-effective amendments, all exhibits thereto, and all
material incorporated by reference or deemed to be incorporated by reference in
such registration statement.

            "Rule 144" means Rule 144 promulgated by the Commission pursuant to
the Securities Act, as such Rule may be amended from time to time, or any
similar rule or regulation hereafter adopted by the Commission having
substantially the same purpose and effect as such Rule.

            "Rule 415" means Rule 415 promulgated by the Commission pursuant to
the Securities Act, as such Rule may be amended from time to time, or any
similar rule or regulation hereafter adopted by the Commission having
substantially the same purpose and effect as such Rule.


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            "Rule 424" means Rule 424 promulgated by the Commission pursuant to
the Securities Act, as such Rule may be amended from time to time, or any
similar rule or regulation hereafter adopted by the Commission having
substantially the same purpose and effect as such Rule.

            "Shares" means the shares of Common Stock issued to the Purchasers
pursuant to the Purchase Agreement.

            "Special Counsel" means Purchaser Counsel who will be reimbursed by
the Company pursuant to Section 4.

            "Warrants" means the Warrants issued under the Purchase Agreement.

            "Warrant Shares" means shares of Common Stock issuable upon exercise
in full of the Warrants.

            2. Registration.

                  (a) On or prior to each Filing Date, the Company shall prepare
and file with the Commission a Registration Statement covering the resale of all
Registrable Securities for an offering to be made on a continuous basis pursuant
to Rule 415. Each Registration Statement shall be on Form S-3 (except if the
Company is not then eligible to register for resale the Registrable Securities
on Form S-3, in which case such registration shall be on another appropriate
form in accordance herewith) and shall contain (except if otherwise directed by
the Holders) the "Plan of Distribution" attached hereto as Annex A. The Company
shall cause such Registration Statement to become effective and remain effective
as provided herein. The Company shall use its best efforts to cause each
Registration Statement to be declared effective under the Securities Act as
promptly as possible after the filing thereof, but in any event prior to its
Effectiveness Date, and shall use its best efforts to keep each Registration
Statement continuously effective under the Securities Act until the date which
is two years after the date that such Registration Statement is declared
effective by the Commission or such earlier date when all Registrable Securities
covered by such Registration Statement have been sold or may be sold without
volume restrictions pursuant to Rule 144(k) as determined by the counsel to the
Company pursuant to a written opinion letter to such effect, addressed and
acceptable to the Company's transfer agent and the affected Holders (the
"Effectiveness Period").

                  (b) If: (a) a Registration Statement is not filed on or prior
to its Filing Date (if the Company files such Registration Statement without
affording the Holder the opportunity to review and comment on the same as
required by Section 3(a), the Company shall not be deemed to have satisfied
clause (a)), or (b) the Company fails to file with the Commission a request for
acceleration in accordance with Rule 461 promulgated under the Securities Act,
within five Trading Days of the date that the Company is notified (orally or in
writing, whichever is earlier) by the Commission that a Registration Statement
will not be "reviewed," or not subject to further review, or (c) the Company
fails to respond to any comments made by the Commission within ten Trading Days
after the receipt of such comments, or (d) a Registration Statement filed
hereunder is not declared effective by the Commission by its Effectiveness Date,
or (e) after a Registration Statement is filed with and declared effective by
the Commission, a


                                      -3-
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Registration Statement ceases to be effective as to all Registrable Securities
to which it is required to relate at any time prior to the expiration of the
Effectiveness Period without being succeeded within ten Trading Days or, if it
would be Materially Detrimental, twenty Trading Days, by an amendment to such
Registration Statement or by a subsequent registration statement which
Registration Statement shall be included within the definition of "Registration
Statement" filed with and declared effective by the Commission, (f) an amendment
to a Registration Statement is not filed by the Company with the Commission
within ten Trading Days or, if it would be Materially Detrimental, twenty
Trading Days, of the Commission's notifying the Company that such amendment is
required in order for a Registration Statement to be declared effective, (any
such failure or breach being referred to as an "Event," and for purposes of
clause (a) or (d) the date on which such Event occurs, or for purposes of clause
(b) the date on which such five Trading Day period is exceeded, or for purposes
of clauses (c), (e) or (f) the date which such ten Trading Day-period or twenty
Trading Day period, as the case may be, is exceeded, being referred to as "Event
Date"), then: (x) on each such Event Date the Company shall pay to each Holder
an amount in cash, as liquidated damages and not as a penalty, equal to 1% of
the aggregate purchase price paid by such Holder pursuant to the Purchase
Agreement; and (y) (if the applicable Event has not been cured by the first
month anniversary following the Event Date, then on such anniversary date) the
Company shall pay to each Holder an amount in cash, as liquidated damages and
not as a penalty, equal to 1% of the aggregate purchase price paid by such
Holder pursuant to the Purchase Agreement and on each monthly anniversary
thereafter until the applicable Event is cured, the Company shall pay to each
Holder an amount in cash, as liquidated damages and not as a penalty, equal to
2% of the aggregate purchase price paid by such Holder pursuant to the Purchase
Agreement provided, however, that all periods shall be tolled during delays
directly caused by the action or inaction of any Holder, and the Company shall
have no liability in respect of any such delay. If the Company fails to pay any
liquidated damages pursuant to this Section in full within seven days after the
date payable, the Company will pay interest thereon at a rate of 18% per annum
(or such lesser maximum amount that is permitted to be paid by applicable law)
to the Holder, accruing daily from the date such liquidated damages are due
until such amounts, plus all such interest thereon, are paid in full.

                  (c) File additional Registration Statements if the number of
Registrable Securities at any time exceeds 85% of the number of shares of Common
Stock then registered in a Registration Statement.

            3. Registration Procedures

            In connection with the Company's registration obligations hereunder,
the Company shall:

                  (a) Not less than (1) five Trading Days prior to the filing of
a Registration Statement or any related Prospectus, (2) three Trading Days prior
to the filing of any pre-effective or post-effective amendment to a Registration
Statement or (3) one Trading Day prior to the filing of any supplement to a
Registration Statement (other than a prospectus supplement the principal purpose
of which is to update the list of selling stockholders), the Company shall, (i)
furnish to the Holders and their Special Counsel copies of all such documents
proposed to be filed (including documents incorporated or deemed incorporated by
reference and


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not available on the EDGAR system) which documents will be subject to the review
of such Holders and their Special Counsel, and (ii) cause its officers and
directors, counsel and independent certified public accountants to respond to
such inquiries as shall be necessary, in the reasonable opinion of respective
counsel to conduct a reasonable investigation within the meaning of the
Securities Act. The Company shall not file a Registration Statement or any such
Prospectus or any amendments or supplements thereto to which the Holders of a
majority of the Registrable Securities and their Special Counsel shall
reasonably object.

                  (b) (i) Prepare and file with the Commission such amendments,
including post-effective amendments, to a Registration Statement and the
Prospectus used in connection therewith as may be necessary to keep a
Registration Statement continuously effective as to the applicable Registrable
Securities for the Effectiveness Period and prepare and file with the Commission
such additional Registration Statements in order to register for resale under
the Securities Act all of the Registrable Securities; (ii) cause the related
Prospectus to be amended or supplemented by any required Prospectus supplement,
and as so supplemented or amended to be filed pursuant to Rule 424; (iii)
respond as promptly as reasonably possible, and in any event within ten Trading
Days, to any comments received from the Commission with respect to a
Registration Statement or any amendment thereto and, as promptly as reasonably
possible provide the Holders true and complete copies of all correspondence from
and to the Commission relating to such Registration Statement; and (iv) comply
in all material respects with the provisions of the Securities Act and the
Exchange Act with respect to the disposition of all Registrable Securities
covered by a Registration Statement during the applicable period in accordance
with the intended methods of disposition by the Holders thereof set forth in
such Registration Statement as so amended or in such Prospectus as so
supplemented.

                  (c) Notify the Holders of Registrable Securities to be sold
and their Special Counsel as promptly as reasonably possible (and, in the case
of (i)(A) below, not less than three Trading Days prior to such filing) and (if
requested by any such Person) confirm such notice in writing no later than one
Trading Day following the day (i)(A) when a Prospectus or any Prospectus
supplement or post-effective amendment to a Registration Statement is proposed
to be filed; (B) when the Commission notifies the Company whether there will be
a "review" of such Registration Statement and whenever the Commission comments
in writing on such Registration Statement (the Company shall provide true and
complete copies thereof and all written responses thereto to each of the
Holders); and (C) with respect to a Registration Statement or any post-effective
amendment, when the same has become effective; (ii) of any request by the
Commission or any other Federal or state governmental authority for amendments
or supplements to a Registration Statement or Prospectus or for additional
information; (iii) of the issuance by the Commission of any stop order
suspending the effectiveness of a Registration Statement covering any or all of
the Registrable Securities or the initiation 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; and (v) of the occurrence of any
event or passage of time that makes the financial statements included in a
Registration Statement ineligible for inclusion therein or any statement made in
such Registration Statement or Prospectus or any document incorporated or deemed
to be incorporated therein by reference untrue in any material respect or that
requires any post-effective amendment to such Registration Statement, or
Prospectus so that, in the case of a


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Registration Statement or the Prospectus, as the case may be, it will 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,
in light of the circumstances under which they were made, not misleading.

                  (d) Use its best efforts to avoid the issuance of, or, if
issued, obtain the withdrawal of (i) any order suspending the effectiveness of a
Registration Statement, or (ii) any suspension of the qualification (or
exemption from qualification) of any of the Registrable Securities for sale in
any jurisdiction, at the earliest practicable moment.

                  (e) Furnish to each Holder and their Special Counsel, without
charge, (i) at least one conformed copy of each Registration Statement and each
amendment thereto, including financial statements and schedules, and (ii) all
documents incorporated or deemed to be incorporated therein by reference, and
all exhibits to the extent requested by such Person (including those previously
furnished or incorporated by reference) promptly after the filing of such
documents with the Commission; provided, that the Company shall have no
obligation to provide any document pursuant to this clause (ii) that is
available on the EDGAR system.

                  (f) Subject to the terms of Section 6(d), the Company shall
promptly deliver to each Holder and their Special Counsel, without charge, as
many copies of the Prospectus or Prospectuses (including each form of
prospectus) and each amendment or supplement thereto as such Persons may
reasonably request. The Company hereby consents to the use of such Prospectus
and each amendment or supplement thereto by each of the selling Holders in
connection with the offering and sale of the Registrable Securities covered by
such Prospectus and any amendment or supplement thereto.

                  (g) Prior to any public offering of Registrable Securities,
use its best efforts to register or qualify or cooperate with the selling
Holders and their Special Counsel 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 Holder requests in
writing, to keep each such registration or qualification (or exemption
therefrom) effective during the Effectiveness Period and to do any and all other
acts or things necessary or advisable to enable the disposition in such
jurisdictions of the Registrable Securities covered by a Registration Statement;
provided, that the Company shall not be required to qualify generally to do
business in any jurisdiction where it is not then so qualified or subject the
Company to any material tax in any such jurisdiction where it is not then so
subject.

                  (h) Cooperate with the Holders to facilitate the timely
preparation and delivery of certificates representing Registrable Securities to
be delivered to a transferee pursuant to a Registration Statement, which
certificates shall be free, to the extent permitted by the Purchase Agreement,
of all restrictive legends, and to enable such Registrable Securities to be in
such denominations and registered in such names as any such Holders may request.

                  (i) Upon the occurrence of any event contemplated by Section
3(c)(v), as promptly as reasonably possible, prepare a supplement or amendment,
including a post-effective amendment, to a Registration Statement or a
supplement to the related Prospectus


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or any document incorporated or deemed to be incorporated therein by reference,
and file any other required document so that, as thereafter delivered, neither
such Registration Statement nor such Prospectus will contain an untrue statement
of a material fact or omit to state a material fact required to be stated
therein or necessary to make the statements therein, in light of the
circumstances under which they were made, not misleading.

                  (j) Comply with all applicable rules and regulations of the
Commission.

                  (k) The Company may require each selling Holder to furnish to
the Company a certified statement as to the number of shares of Common Stock
beneficially owned by such Holder and, if requested by the Commission, the
controlling person thereof.

            4. Registration Expenses. All fees and expenses incident to the
performance of or compliance with this Agreement by the Company shall be borne
by the Company whether or not any Registrable Securities are sold pursuant to a
Registration Statement. The fees and expenses referred to in the foregoing
sentence shall include, without limitation, (i) all registration and filing fees
(including, without limitation, fees and expenses (A) with respect to filings
required to be made with the Trading Market on which the Common Stock is then
listed for trading, and (B) in compliance with applicable state securities or
Blue Sky laws), (ii) printing expenses (including, without limitation, expenses
of printing certificates for Registrable Securities and of printing prospectuses
if the printing of prospectuses is reasonably requested by the holders of a
majority of the Registrable Securities included in a Registration Statement),
(iii) messenger, telephone and delivery expenses, (iv) fees and disbursements of
counsel for the Company and $10,000 of the fees and disbursements of Special
Counsel for the Holders, (v) Securities Act liability insurance, if the Company
so desires such insurance, and (vi) fees and expenses of all other Persons
retained by the Company in connection with the consummation of the transactions
contemplated by this Agreement. In addition, the Company shall be responsible
for all of its internal expenses incurred in connection with the consummation of
the transactions contemplated by this Agreement (including, without limitation,
all salaries and expenses of its officers and employees performing legal or
accounting duties), the expense of any annual audit and the fees and expenses
incurred in connection with the listing of the Registrable Securities on any
securities exchange as required hereunder.

            5. Indemnification

                  (a) Indemnification by the Company. The Company shall,
notwithstanding any termination of this Agreement, indemnify and hold harmless
each Holder, the officers, directors, agents and employees of each of them, each
Person who controls any such Holder (within the meaning of Section 15 of the
Securities Act or Section 20 of the Exchange Act) and the officers, directors,
agents and employees of each such controlling Person, to the fullest extent
permitted by applicable law, from and against any and all losses, claims,
damages, liabilities, costs (including, without limitation, reasonable costs of
preparation and reasonable attorneys' fees) and expenses (collectively,
"Losses"), as incurred, arising out of or relating to any untrue or alleged
untrue statement of a material fact contained in a Registration Statement, any
Prospectus or in any amendment or supplement thereto arising out of or relating
to any omission or alleged omission of a material fact required to be stated
therein or necessary to make


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<PAGE>

the statements therein (in the case of any Prospectus or supplement thereto, in
light of the circumstances under which they were made) not misleading, except to
the extent, but only to the extent, that (1) such untrue statements or omissions
are based solely upon information regarding such Holder furnished in writing to
the Company by such Holder expressly for use therein, or to the extent that such
information relates to such Holder or such Holder's proposed method of
distribution of Registrable Securities and was reviewed and expressly approved
in writing by such Holder expressly for use in a Registration Statement, such
Prospectus or in any amendment or supplement thereto (it being understood that
the Holder has approved Annex A hereto for this purpose) or (2) in the case of
an occurrence of an event of the type specified in Section 3(c)(ii)-(v), the use
by such Holder of an outdated or defective Prospectus after the Company has
notified such Holder in writing that the Prospectus is outdated or defective and
prior to the receipt by such Holder of the Advice contemplated in Section 6(d).
The Company shall notify the Holders promptly of the institution, threat or
assertion of any Proceeding of which the Company is aware in connection with the
transactions contemplated by this Agreement.

                  (b) Indemnification by Holders. Each Holder shall, severally
and not jointly, indemnify and hold harmless the Company, its directors,
officers, agents and employees, each Person who controls the Company (within the
meaning of Section 15 of the Securities Act and Section 20 of the Exchange Act),
and the directors, officers, agents or employees of such controlling Persons, to
the fullest extent permitted by applicable law, from and against all Losses, as
incurred, arising solely out of or based solely upon: (x) such Holder's failure
to comply with the prospectus delivery requirements of the Securities Act or (y)
any untrue statement of a material fact contained in any Registration Statement,
any Prospectus, or in any amendment or supplement thereto, or arising solely out
of or based solely upon any omission of a material fact required to be stated
therein or necessary to make the statements therein not misleading to the
extent, but only to the extent, that such untrue statement or omission is
contained in any information so furnished in writing by such Holder to the
Company specifically for inclusion in such Registration Statement or such
Prospectus or to the extent that (1) such untrue statements or omissions are
based solely upon information regarding such Holder furnished in writing to the
Company by such Holder expressly for use therein, or to the extent that such
information relates to such Holder or such Holder's proposed method of
distribution of Registrable Securities and was reviewed and expressly approved
in writing by such Holder expressly for use in a Registration Statement (it
being understood that the Holder has approved Annex A hereto for this purpose),
such Prospectus or in any amendment or supplement thereto or (2) in the case of
an occurrence of an event of the type specified in Section 3(c)(ii)-(v), the use
by such Holder of an outdated or defective Prospectus after the Company has
notified such Holder in writing that the Prospectus is outdated or defective and
prior to the receipt by such Holder of the Advice contemplated in Section 6(d).
In no event shall the liability of any selling Holder hereunder be greater in
amount than the dollar amount of the net proceeds received by such Holder upon
the sale of the Registrable Securities giving rise to such indemnification
obligation.

                  (c) Conduct of Indemnification Proceedings. If any Proceeding
shall be brought or asserted against any Person entitled to indemnity hereunder
(an "Indemnified Party"), such Indemnified Party shall promptly notify the
Person from whom indemnity is sought (the "Indemnifying Party") in writing, and
the Indemnifying Party shall assume the defense thereof, including the
employment of counsel reasonably satisfactory to the Indemnified Party


                                      -8-
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and the payment of all fees and expenses incurred in connection with defense
thereof; provided, that the failure of any Indemnified Party to give such notice
shall not relieve the Indemnifying Party of its obligations or liabilities
pursuant to this Agreement, except (and only) to the extent that such failure
shall have proximately and materially adversely prejudiced the Indemnifying
Party.

            An Indemnified Party shall have the right to employ separate counsel
in any such Proceeding and to participate in the defense thereof, but the fees
and expenses of such counsel shall be at the expense of such Indemnified Party
or Parties unless: (1) the Indemnifying Party has agreed in writing to pay such
fees and expenses; (2) the Indemnifying Party shall have failed promptly to
assume the defense of such Proceeding and to employ counsel reasonably
satisfactory to such Indemnified Party in any such Proceeding; or (3) the named
parties to any such Proceeding (including any impleaded parties) include both
such Indemnified Party and the Indemnifying Party, and such Indemnified Party
shall have been advised in writing by counsel that a conflict of interest is
likely to exist if the same counsel were to represent such Indemnified Party and
the Indemnifying Party (in which case, if such Indemnified Party notifies the
Indemnifying Party in writing that it elects to employ separate counsel at the
expense of the Indemnifying Party, the Indemnifying Party shall not have the
right to assume the defense thereof and such counsel shall be at the expense of
the Indemnifying Party); provided, that the Indemnifying Party shall not be
liable for the fees and expenses of more than one separate firm of attorneys at
any time for all indemnified parties. The Indemnifying Party shall not be liable
for any settlement of any such Proceeding effected without its written consent,
which consent shall not be unreasonably withheld. No Indemnifying Party shall,
without the prior written consent of the Indemnified Party, effect any
settlement of any pending Proceeding in respect of which any Indemnified Party
is a party, unless such settlement includes an unconditional release of such
Indemnified Party from all liability on claims that are the subject matter of
such Proceeding.

            All fees and expenses of the Indemnified Party (including reasonable
fees and expenses to the extent incurred in connection with investigating or
preparing to defend such Proceeding in a manner not inconsistent with this
Section) shall be paid to the Indemnified Party, as incurred, within ten Trading
Days of written notice thereof to the Indemnifying Party (regardless of whether
it is ultimately determined that an Indemnified Party is not entitled to
indemnification hereunder; provided, that the Indemnified Party shall reimburse
all such fees and expenses to the extent it is finally judicially determined
that such Indemnified Party is not entitled to indemnification hereunder).

                  (d) Contribution. If a claim for indemnification under Section
5(a) or 5(b) is unavailable to an Indemnified Party (by reason of public policy
or otherwise), then each Indemnifying Party, in lieu of indemnifying such
Indemnified Party, shall contribute to the amount paid or payable by such
Indemnified Party as a result of such Losses, in such proportion as is
appropriate to reflect the relative fault of the Indemnifying Party and
Indemnified Party in connection with the actions, statements or omissions that
resulted in such Losses as well as any other relevant equitable considerations.
The relative fault of such Indemnifying Party and Indemnified Party shall be
determined by reference to, among other things, whether any action in question,
including any untrue or alleged untrue statement of a material fact or omission
or alleged omission of a material fact, has been taken or made by, or relates to
information supplied


                                      -9-
<PAGE>

by, such Indemnifying Party or Indemnified Party, and the parties' relative
intent, knowledge, access to information and opportunity to correct or prevent
such action, statement or omission. The amount paid or payable by a party as a
result of any Losses shall be deemed to include, subject to the limitations set
forth in Section 5(c), any reasonable attorneys' or other reasonable fees or
expenses incurred by such party in connection with any Proceeding to the extent
such party would have been indemnified for such fees or expenses if the
indemnification provided for in this Section was available to such party in
accordance with its terms.

            The parties hereto agree that it would not be just and equitable if
contribution pursuant to this Section 5(d) were determined by pro rata
allocation or by any other method of allocation that does not take into account
the equitable considerations referred to in the immediately preceding paragraph.
Notwithstanding the provisions of this Section 5(d), no Holder shall be required
to contribute, in the aggregate, any amount in excess of the amount by which the
proceeds actually received by such Holder from the sale of the Registrable
Securities subject to the Proceeding 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.

            The indemnity and contribution agreements contained in this Section
are in addition to any liability that the Indemnifying Parties may have to the
Indemnified Parties.

            6. Miscellaneous

                  (a) Remedies. In the event of a breach by the Company or by a
Holder, of any of their obligations under this Agreement, each Holder or the
Company, as the case may be, in addition to being entitled to exercise all
rights granted by law and under this Agreement, including recovery of damages,
will be entitled to specific performance of its rights under this Agreement. The
Company and each Holder agree that monetary damages would not provide adequate
compensation for any losses incurred by reason of a breach by it of any of the
provisions of this Agreement and hereby further agrees that, in the event of any
action for specific performance in respect of such breach, it shall waive the
defense that a remedy at law would be adequate.

                  (b) No Piggyback on Registrations. Except as and to the extent
specified in Schedule 6(b) hereto, neither the Company nor any of its security
holders (other than the Holders in such capacity pursuant hereto) may include
securities of the Company in a Registration Statement other than the Registrable
Securities, and the Company shall not after the date hereof enter into any
agreement providing any such right to any of its security holders. Except as and
to the extent specified in Schedule 6(b) hereto, the Company has not previously
entered into any agreement granting any registration rights with respect to any
of its securities to any Person which have not been fully satisfied.

                  (c) Compliance. Each Holder covenants and agrees that it will
comply with the prospectus delivery requirements of the Securities Act as
applicable to it in connection with sales of Registrable Securities pursuant to
a Registration Statement.


                                      -10-
<PAGE>

                  (d) Discontinued Disposition. Each Holder agrees by its
acquisition of such Registrable Securities that, upon receipt of a notice from
the Company of the occurrence of any event of the kind described in Section
3(c), such Holder will forthwith discontinue disposition of such Registrable
Securities under a Registration Statement until such Holder's receipt of the
copies of the supplemented Prospectus and/or amended Registration Statement or
until it is advised in writing (the "Advice") by the Company that the use of the
applicable Prospectus may be resumed, and, in either case, has received copies
of any additional or supplemental filings that are incorporated or deemed to be
incorporated by reference in such Prospectus or Registration Statement. The
Company may provide appropriate stop orders to enforce the provisions of this
paragraph.

                  (e) Piggy-Back Registrations. If at any time during the
Effectiveness Period there is not an effective Registration Statement covering
all of the Registrable Securities and the Company shall determine to prepare and
file with the Commission a registration statement relating to an offering for
its own account or the account of others under the Securities Act of any of its
equity securities, other than on Form S-4 or Form S-8 (each as promulgated under
the Securities Act) or their then equivalents relating to equity securities to
be issued solely in connection with any acquisition of any entity or business or
equity securities issuable in connection with stock option or other employee
benefit plans, then the Company shall send to each Holder written notice of such
determination and, if within fifteen days after receipt of such notice, any such
Holder shall so request in writing, the Company shall include in such
registration statement all or any part of such Registrable Securities such
holder requests to be registered, subject to customary underwriter cutbacks
applicable to all holders of registration rights.

                  (f) 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 same shall be in writing and signed by the Company
and the Holders of the then outstanding Registrable Securities. 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 certain Holders
and that does not directly or indirectly affect the rights of other Holders may
be given by Holders of at least a majority of the Registrable Securities to
which such waiver or consent relates; provided, however, that the provisions of
this sentence may not be amended, modified, or supplemented except in accordance
with the provisions of the immediately preceding sentence.

                  (g) Notices. Any and all notices or other communications or
deliveries required or permitted to be provided hereunder shall be in writing
and shall be deemed given and effective on the earliest of (i) the date of
transmission, if such notice or communication is delivered via facsimile at the
facsimile number specified in this Section prior to 6:30 p.m. (New York City
time) on a Trading Day, (ii) the Trading Day after the date of transmission, if
such notice or communication is delivered via facsimile at the facsimile number
specified in this Agreement later than 6:30 p.m. (New York City time) on any
date and earlier than 11:59 p.m. (New York City time) on such date, (iii) the
Trading Day following the date of mailing, if sent by nationally recognized
overnight courier service, or (iv) upon actual receipt by the party to whom such
notice is required to be given. The address for such notices and communications
shall be as follows:


                                      -11-
<PAGE>

        If to the Company:          Hyseq, Inc.
                                    670 Almanor Avenue
                                    Sunnyvale, CA 94085
                                    Facsimile No.: (408) 524-8141
                                    Attn: President

        With a copy to:             Latham & Watkins
                                    135 Commonwealth Drive
                                    Menlo Park, CA 94025
                                    Facsimile No.: (650) 463-2600
                                    Attn: Alan C. Mendelson

        If to a Purchaser:   To the address set forth under such
                             Purchaser's name on the signature pages hereto.

        With a copy to:      Robinson Silverman Pearce Aronsohn & Berman LLP
                             1290 Avenue of the Americas
                             New York, NY  10104
                             Facsimile No.: (212) 541-4630 and (212) 541-1432
                             Attn: Eric L. Cohen, Esq.

        If to any other Person who is then the registered Holder:

                             To the address of such Holder as it appears in the
                             stock transfer books of the Company

            or such other address as may be designated in writing hereafter, in
the same manner, by such Person.

                  (h) Successors and Assigns. This Agreement shall inure to the
benefit of and be binding upon the successors and permitted assigns of each of
the parties and shall inure to the benefit of each Holder. The Company may not
assign its rights or obligations hereunder without the prior written consent of
each Holder. Each Holder may assign their respective rights hereunder in the
manner and to the Persons as permitted under the Purchase Agreement.

                  (i) Execution and Counterparts. This Agreement may be executed
in any number of counterparts, each of which when so executed shall be deemed to
be an original and, all of which taken together shall constitute one and the
same Agreement. In the event that any signature is delivered by facsimile
transmission, such signature shall create a valid binding obligation of the
party executing (or on whose behalf such signature is executed) the same with
the same force and effect as if such facsimile signature were the original
thereof.

                  (j) Governing Law. All questions concerning the construction,
validity, enforcement and interpretation of this Agreement shall be governed by
and construed and enforced in accordance with the internal laws of the State of
New York, without regard to the principles of conflicts of law thereof. Each
party agrees that all Proceedings concerning the interpretations, enforcement
and defense of the transactions contemplated by this Agreement


                                      -12-
<PAGE>

(whether brought against a party hereto or its respective affiliates, directors,
officers, shareholders, employees or agents) shall be commenced exclusively in
the state and federal courts sitting in the City of New York, Borough of
Manhattan. Each party hereto hereby irrevocably submits to the exclusive
jurisdiction of the state and federal courts sitting in the City of New York,
Borough of Manhattan for the adjudication of any dispute hereunder or in
connection herewith or with any transaction contemplated hereby or discussed
herein (including with respect to the enforcement of any of this Agreement), and
hereby irrevocably waives, and agrees not to assert in any Proceeding, any claim
that it is not personally subject to the jurisdiction of any such court, that
such Proceeding venue is improper. Each party hereto hereby irrevocably waives
personal service of process and consents to process being served in any such
Proceeding by mailing a copy thereof via registered or certified mail or
overnight delivery (with evidence of delivery) to such party at the address in
effect for notices to it under this Agreement and agrees that such service shall
constitute good and sufficient service of process and notice thereof. Nothing
contained herein shall be deemed to limit in any way any right to serve process
in any manner permitted by law. Each party hereto hereby irrevocably waives, to
the fullest extent permitted by applicable law, any and all right to trial by
jury in any legal proceeding arising out of or relating to this Agreement or the
transactions contemplated hereby. If either party shall commence a Proceeding to
enforce any provisions of this Agreement, then the prevailing party in such
Proceeding shall be reimbursed by the other party for its attorneys fees and
other costs and expenses incurred with the investigation, preparation and
prosecution of such Proceeding.

                  (k) Cumulative Remedies. The remedies provided herein are
cumulative and not exclusive of any remedies provided by law.

                  (l) Severability. If any term, provision, covenant or
restriction of this Agreement is held by a court of competent jurisdiction 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, and the parties
hereto shall use their 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 is hereby stipulated and
declared to be the intention of the parties that they would have executed the
remaining terms, provisions, covenants and restrictions without including any of
such that may be hereafter declared invalid, illegal, void or unenforceable.

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

                  (n) Independent Nature of Purchasers' Obligations and Rights.
The obligations of each Purchaser hereunder is several and not joint with the
obligations of any other Purchaser hereunder, and no Purchaser shall be
responsible in any way for the performance of the obligations of any other
Purchaser hereunder. Nothing contained herein or in any other agreement or
document delivered at any closing, and no action taken by any Purchaser pursuant
hereto or thereto, shall be deemed to constitute the Purchasers as a
partnership, an association, a joint venture or any other kind of entity, or
create a presumption that the Purchasers are in any way acting in concert with
respect to such obligations or the transactions contemplated by this Agreement.
Each Purchaser shall be entitled to protect and enforce its rights, including
without


                                      -13-
<PAGE>

limitation the rights arising out of this Agreement, and it shall not be
necessary for any other Purchaser to be joined as an additional party in any
proceeding for such purpose.

                   [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK
                           SIGNATURE PAGES TO FOLLOW]


                                      -14-
<PAGE>

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

                                        HYSEQ, INC.

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



                   [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK
                     SIGNATURE PAGES OF PURCHASER TO FOLLOW]


<PAGE>

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

                                        [PURCHASER]


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


                                        Address for Notice:
                                        [ ]


                                        With a copy to:


                                        Robinson Silverman Pearce Aronsohn &
                                        Berman LLP
                                        1290 Avenue of the Americas
                                        New York, NY 10104
                                        Facsimile No.: (212) 541-4630 and
                                                       (212) 541-1432
                                        Attn: Eric L. Cohen, Esq.


<PAGE>

                                                                         Annex A

                              Plan of Distribution

      The Selling Stockholders and any of their pledgees, assignees and
successors-in-interest may, from time to time, sell any or all of their shares
of Common Stock on any stock exchange, market or trading facility on which the
shares are traded or in private transactions. These sales may be at fixed or
negotiated prices. The Selling Stockholders may use any one or more of the
following methods when selling shares:

      -     ordinary brokerage transactions and transactions in which the
            broker-dealer solicits purchasers;

      -     block trades in which the broker-dealer will attempt to sell the
            shares as agent but may position and resell a portion of the block
            as principal to facilitate the transaction;

      -     purchases by a broker-dealer as principal and resale by the
            broker-dealer for its account;

      -     an exchange distribution in accordance with the rules of the
            applicable exchange;

      -     privately negotiated transactions;

      -     short sales

      -     broker-dealers may agree with the Selling Stockholders to sell a
            specified number of such shares at a stipulated price per share;

      -     a combination of any such methods of sale; and

      -     any other method permitted pursuant to applicable law.

      The Selling Stockholders may also sell shares under Rule 144 under the
Securities Act, if available, rather than under this prospectus.

      Broker-dealers engaged by the Selling Stockholders may arrange for other
brokers-dealers to participate in sales. Broker-dealers may receive commissions
or discounts from the Selling Stockholders (or, if any broker-dealer acts as
agent for the purchaser of shares, from the purchaser) in amounts to be
negotiated. The Selling Stockholders do not expect these commissions and
discounts to exceed what is customary in the types of transactions involved.

      The selling stockholder may from time to time pledge or grant a security
interest in some or all of the Shares or common stock or Warrant owned by them
and, if they default in the performance of their secured obligations, the
pledgees or secured parties may offer and sell the shares of common stock from
time to time under this prospectus, or under an amendment to this prospectus
under Rule 424(b)(3) or other applicable provision of the Securities Act of 1933
amending the list of selling stockholders to include the pledgee, transferee or
other successors in interest as selling stockholders under this prospectus.


<PAGE>

      The selling stockholders also may transfer the shares of common stock in
other circumstances, in which case the transferees, pledgees or other successors
in interest will be the selling beneficial owners for purposes of this
prospectus.

      The Selling Stockholders and any broker-dealers or agents that are
involved in selling the shares may be deemed to be "underwriters" within the
meaning of the Securities Act in connection with such sales. In such event, any
commissions received by such broker-dealers or agents and any profit on the
resale of the shares purchased by them may be deemed to be underwriting
commissions or discounts under the Securities Act. The Selling Stockholders have
informed the Company that it does not have any agreement or understanding,
directly or indirectly, with any person to distribute the Common Stock.

      The Company has advised the Selling Stockholders that they are required to
comply with Regulation M promulgated under the Securities and Exchange Act
during such time as they may be engaged in a distribution of the shares. With
some exceptions, Regulation M precludes any Selling Stockholders, any affiliated
purchasers and any broker-dealer or other person who participates in such
distribution from bidding for or purchasing, or attempting to induce any person
to bid for or purchase any security that is the subject of the distribution
until the entire distribution is complete. Regulation M also prohibits any bids
or purchases made in order to stabilize the price of a security in connection
with the distribution of that security. All of the foregoing may affect the
marketability of the common stock.

      The Company is required to pay all fees and expenses incident to the
registration of the shares, including $10,000 of fees and disbursements of
counsel to the Selling Stockholders. The Company has agreed to indemnify the
Selling Stockholders against certain losses, claims, damages and liabilities,
including liabilities under the Securities Act.