REGISTRATION RIGHTS AGREEMENT

         This Registration Rights Agreement (the "Agreement") is made and
entered into as of January 19, 2000 between GENENTECH, INC., a Delaware
corporation ("Genentech"), and Merrill Lynch & Co., Merrill Lynch, Pierce,
Fenner & Smith Incorporated, a Delaware corporation (the "Purchaser").

      This Agreement is made pursuant to the Private Placement Purchase
Agreement, dated as of January 12, 2000 (the "Purchase Agreement"), between
Roche Holdings, Inc. ("Roche Holdings") and the Purchaser, which provides for
the sale by Roche Holdings to the Purchaser of $1,506,342,000 aggregate
principal amount at maturity of Roche Holdings' Liquid Yield Option(TM)Notes due
January 19, 2015 (Zero Coupon) (the "LYONs") and the Agreement dated as of
January 12, 2000 between Genentech and the Purchaser (the "Genentech
Agreement"). For good and valuable consideration, the receipt and sufficiency of
which are hereby acknowledged by Genentech, Genentech 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. In the Purchase
Agreement, Roche Holdings has agreed to take certain actions in furtherance of
the agreements of Genentech set forth in this Agreement.

      The parties hereby agree as follows:

         SECTION 1. Definitions. As used in this Agreement, the following terms
shall have the following meanings:

         Business Day: Each Monday, Tuesday, Wednesday, Thursday and Friday
which is not a day on which banking institutions in New York or London are
closed.

         Closing Date: January 19, 2000, or such other date as may be agreed
upon for the sale and purchase of the LYONs pursuant to the Purchase Agreement.

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

         Exchange Agent: Any person appointed by Roche Holdings as provided in
Section 902 of the Indenture to exchange LYONs.

         Genentech Common Stock: Common stock, par value $0.02 per share, of
Genentech.

         Indenture: The Indenture, to be dated as of January 19, 2000, between
Roche Holdings and The Bank of New York, as Trustee, pursuant to which the LYONs
are being issued, as amended or supplemented from time to time in accordance
with the terms thereof.


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      Person: An individual, partnership, limited liability company,
corporation, association, trust, joint venture or any other unincorporated
organization or entity.

      Prospectus: 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 430A), as amended or supplemented by any
prospectus supplement, with respect to the terms of the offering of any portion
of the Registrable Securities covered by such Registration Statement, and all
other amendments and supplements to the Prospectus, including post-effective
amendments and all material incorporated by reference or deemed to be
incorporated by reference in such Prospectus.

      Registrable Securities: Shares of Genentech Common Stock issuable upon
exchange of LYONs that are Restricted Securities.

      Registration Expenses: See Section 5 hereof.

      Registration Statement: Any registration statement of Genentech 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 material incorporated by reference or deemed to be incorporated by reference
in such registration statement.

      Restricted Securities: Any and all shares of Genentech Common Stock
issuable upon exchange of LYONs and at all times subsequent thereto until, as to
any Restricted Security, (i) the sale of such Restricted Security has been
effectively registered under the Securities Act and such Restricted Security has
been disposed of in accordance with the method of distribution set forth in the
Registration Statement relating thereto, or (ii) it is distributed to the
public, or is otherwise able to be sold, pursuant to Rule 144(k) (or any similar
provision then in force, but not Rule 144A) under the Securities Act.

      SEC:  The Securities and Exchange Commission.

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

      Shelf Registration:  See Section 3 hereof.

      Special Counsel: Shearman & Sterling, special counsel to the Purchaser or
such other special counsel as may be designated by the holders of a majority
(with holders of LYONs deemed to be the holders, for purposes of determining
such majority, of the number of shares of Registrable Securities into which such
LYONs would be exchangeable as of the date such designation is made) of shares
of Registrable Securities outstanding.


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      Trustee: The Bank of New York until a successor Trustee shall have become
such pursuant to the applicable provisions of the Indenture, and thereafter
Trustee shall mean such successor Trustee.

      SECTION 2.  Securities Subject to this Agreement.

      (a) Securities. The securities entitled to the benefits of this Agreement
are the Registrable Securities.

      (b) Holders of Registrable Securities. A Person is deemed to be a holder
of Registrable Securities whenever such Person beneficially owns Registrable
Securities.

      SECTION 3.  Shelf Registrations.

      (a) Shelf Registrations. As promptly as practicable and, subject to
Section 4(a), in no event later than 120 days after the date hereof, Genentech
shall use reasonable efforts to prepare and file with the SEC a Registration
Statement (which may include any previously filed Registration Statement meeting
the requirements set forth herein) under the Securities Act for an offering to
be made on a continuous basis pursuant to Rule 415 (or any similar rule that may
be adopted by the SEC) under the Securities Act covering all of the Registrable
Securities (the "Shelf Registration").

      (b) The Shelf Registration shall be on Form S-3 or another appropriate
form permitting registration of such Registrable Securities for resale by such
holders in the manner or manners designated by them.

      (c) Genentech shall use reasonable efforts to cause the Shelf Registration
to become effective under the Securities Act as soon as practicable after filing
in accordance with Section 3(a) hereof and shall keep the Shelf Registration
continuously effective until the earlier of (i) the sale pursuant to the Shelf
Registration statement of all the securities registered thereunder, (ii) the
expiration of the holding period under Section 144(k) of the Securities Act
applicable to Registrable Securities after the exchange of the last outstanding
LYON for Registrable Securities, (iii) the date all Registrable Securities cease
to exist and (iv) two years after maturity of the LYONs.

      (d) Genentech may suspend use of the Prospectus due to pending material
corporate developments or any material event that has not yet been publicly
disclosed, whether in whole or in part. Promptly after any such suspension,
Genentech will deliver a certificate in writing, signed by an authorized officer
of Genentech, to Roche Holdings, the holders of Registrable Securities, the
Trustee, the Exchange Agent and the Special Counsel setting forth that such an
event (without notice of the nature or details of such event) has taken or is
taking place and the length of time of suspension of the use of the Prospectus
that is part of the Shelf Registration statement. Genentech will use reasonable
efforts to ensure that use of the Shelf Registration statement may be resumed as
promptly as is practicable. The period of time that the Shelf Registration
statement is not available for sales as a result of events under this Section
3(d) shall not exceed in the aggregate 45 days in any 3 month period and 90 days
in any 12 month period. Genentech shall also supplement or make

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<PAGE>


amendments to any Shelf Registration if required by the rules, regulations or
instructions applicable to the registration form used by Genentech or if
required by the Securities Act.

      SECTION 4. Registration Procedures. In connection with the registration
obligations pursuant to Section 3 hereof, Genentech shall use reasonable efforts
to effect such registration to permit the sale of such Registrable Securities in
accordance with the then intended method or methods of disposition thereof
(which shall not include an underwritten offering), and pursuant thereto
Genentech shall as expeditiously as possible:

      (a) prepare and file with the SEC, within the time period specified in
Section 3, a Registration Statement or Registration Statements on any
appropriate form under the Securities Act, which form shall be 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 all reasonable
efforts to cause each such Registration Statement to become effective and remain
effective as provided herein; provided, however, that before filing a
Registration Statement or Prospectus or any amendments or supplements thereto,
Genentech shall furnish to the Special Counsel copies of the Registration
Statement or Prospectus and all such documents in the form proposed to be filed
at least three Business Days prior thereto, which documents will be subject to
the review of the Special Counsel, and Genentech shall not file any such
Registration Statement or amendment thereto or any Prospectus or any supplement
thereto to which the Special Counsel shall reasonably object on a timely basis
(such objection shall be given within five Business Days from the date such
Special Counsel receives such Registration Statement, amendment, Prospectus or
supplement and if such objection cannot be resolved with good faith efforts
within five days from the date such objection is sent, then the 120 day period
referred to in Section 3(a) shall be tolled until such objection is resolved),
unless Genentech is advised by its counsel that such Registration Statement or
amendment thereto or any Prospectus or supplement thereto is required to be
filed by applicable law;

      (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 for the applicable 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;

      (c) promptly notify the Special Counsel, the Exchange Agent, the Trustee
and Roche Holdings and, with respect to any event contemplated by clause (i)(B),
(iv), (v) or (vi) hereof, notify holders of Registrable Securities promptly (and
in each case, if requested, confirm any such oral or telephonic notice in
writing), (i) when a Prospectus or any Prospectus supplement or post-effective
amendment related to such Registrable Securities (A) has been filed, and (B)
with respect to a Registration Statement or any post-effective amendment related
to such Registrable Securities, when the same has been filed and has become
effective, (ii) of the receipt of any comments from the SEC, (iii) of any
request by the SEC for amendments or supplements to a Registration Statement or
related Prospectus or for additional information, (iv) of the issuance by the
SEC of any stop order suspending the effectiveness of a Registration Statement
or the initiation of any proceedings for that purpose, (v) of the receipt by
Genentech of any notification with respect to the suspension of the
qualification or exemption from qualification of any of the Registrable
Securities for sale or


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exchange in any jurisdiction of the United States of America or the initiation
of any proceeding for such purpose, (vi) of the happening of any event that
makes any statement of a material fact made in such Registration Statement or
related Prospectus or any document incorporated or deemed to be incorporated
therein by reference untrue or that requires the making of any changes in a
Registration Statement or related Prospectus so that such documents 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
(provided that the timely filing of a report under the Exchange Act which is
incorporated by reference in the Registration Statement and related Prospectus
shall constitute effective notice under this subsection (vi); and provided
further, that such notice may be the same notice delivered pursuant to Section
3(d); and provided further that notice that an event of the type referred to in
this subsection (vi) (without notice of the nature or details of such event)
shall constitute effective notice under this subsection (vi)), and (vii) of the
determination of Genentech that a post-effective amendment to a Registration
Statement would be appropriate;

      (d) use reasonable efforts 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 or exchange in any jurisdiction of the United
States of America, as promptly as practicable;

      (e) if reasonably requested by any holder of Registrable Securities
covered by a Registration Statement, (i) promptly incorporate in a Prospectus
supplement or post-effective amendment such information as such holder
reasonably requests to be included therein as is required by applicable law or
as necessary so that the Registration Statement does not include an untrue
statement of a material fact or omit to state a material fact with respect to
such holder or such holder's planned method of distribution, (ii) make all
required filings of such Prospectus supplement or such post- effective amendment
as soon as Genentech has received notification of the matters to be incorporated
in such Prospectus supplement or such post-effective amendment, and (iii)
supplement or make amendments to any Registration Statement as is required by
applicable law;

      (f) furnish to each selling holder of Registrable Securities upon request,
and to each of Roche Holdings and the Special Counsel, without charge (subject
to the provisions of Section 5), at least one conformed copy of the Registration
Statement or Statements and any post-effective amendment thereto, including
financial statements and schedules, without charge, as well as all documents
incorporated therein by reference or deemed incorporated therein by reference
and all exhibits (including those previously furnished or incorporated by
reference), at the earliest practicable time under the circumstances after the
filing of such documents with the SEC;

      (g) deliver to each holder of Registrable Securities, Roche Holdings and
the Special Counsel, without charge (subject to the provisions of Section 5), as
many copies of the Prospectus or Prospectuses (including each preliminary
prospectus) and any relevant amendment or supplement thereto as such Persons may
reasonably request; Genentech consents to the use of such Prospectus or any
amendment or supplement thereto in accordance with applicable law and this
Agreement by each of the selling holders of Registrable Securities in connection
with the offering and sale of the


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Registrable Securities covered by such Prospectus or any amendment or supplement
thereto in accordance with applicable law and this Agreement;

      (h) prior to any public offering of Registrable Securities, use reasonable
efforts to register or qualify or cooperate with the selling holders of
Registrable Securities and the Special Counsel in connection with the
registration or qualification (or exemption from such registration or
qualification) of such Registrable Securities for offer and sale, as the case
may be, under the securities or Blue Sky laws of such state or local
jurisdictions in the United States as any seller reasonably requests in writing;
keep each such registration or qualification (or exemption therefrom) effective
during the period such Registration Statement is required to be kept effective
and do any and all other acts or things necessary or advisable to enable the
disposition in such jurisdictions of the Registrable Securities covered by the
applicable Registration Statement; provided, however, that Genentech will not be
required to (i) qualify generally to do business in any jurisdiction where it is
not then so qualified, (ii) take any action that would subject it to general
service of process in any such jurisdiction where it is not then so subject or
(iii) register or qualify securities prior to the effective date of any
Registration Statement under Section 3 hereof;

      (i) cooperate with the selling holders of Registrable Securities to
facilitate the timely preparation and delivery of certificates representing
Registrable Securities, which certificates shall not bear any restrictive
legends; and enable such Registrable Securities to be registered in such names,
in all cases consistent with the requirements set forth in the Indenture, as the
holders may request;

      (j) subject to the exceptions contained in (i), (ii) and (iii) of
subsection (h) hereof, use all reasonable efforts to cause the Registrable
Securities covered by the applicable Registration Statement to be registered
with or approved by such other Federal, state and local governmental regulatory
agencies or authorities in the United States as may be necessary, by virtue of
the business and operations of Genentech, to enable the seller or sellers
thereof to consummate the disposition of such Registrable Securities and
cooperate with each seller of Registrable Securities in connection with any
filings required to be made with the National Association of Securities Dealers,
Inc.;

      (k) subject to the suspension of the use of the Prospectus that is part of
the Shelf Registration statement in accordance with Section 3(d), upon the
occurrence of any event contemplated by paragraph 4(c)(vi) or 4(c)(vii) above,
as promptly as practicable after the resolution of such an event as determined
by Genentech in good faith, prepare and file with the SEC a supplement or post-
effective amendment to the applicable Registration Statement or a supplement to
the related Prospectus or any document incorporated therein by reference or file
any other required document so that, as thereafter delivered to the purchasers
of the Registrable Securities being sold thereunder, such Prospectus will not
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;

      (l) take all customary actions in order to expedite or facilitate the
disposition of such Registrable Securities; and


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      (m) comply with all applicable rules and regulations of the SEC and make
generally available to Genentech's securityholders an earnings statement
satisfying the provisions of Section 11(a) of the Securities Act and Rule 158
thereunder no later than the date required for the filing of the applicable
forms referred to in Rule 158, commencing on the first day of the first fiscal
quarter of Genentech commencing after the effective date of a Registration
Statement, which statement shall cover said 12-month period.

      Purchaser shall, as a condition to the sale of any Registrable Security,
require the holder to whom such Registrable Security is sold to agree to be
bound by this Agreement with respect to the obligations of holders of
Registrable Securities set forth herein. Genentech may require each selling
holder of Registrable Securities under a Shelf Registration to furnish to
Genentech such information regarding such selling holder and the distribution of
such Registrable Securities, including the information specified in Item 507 of
Regulation S-K under the Securities Act, as Genentech may from time to time
reasonably request in writing, and each holder in acquiring such Registrable
Securities agrees to supply such information to Genentech promptly upon such
request.

      Each holder of Registrable Securities agrees by acquisition of such
Registrable Securities that (i) within three Business Days of such acquisition,
such holder shall provide Genentech, with a copy to the Trustee and the Exchange
Agent, with such holder's name, address and telecopier number, if any, (ii) such
holder will promptly (and in any case within two Business Days after completion
of such sale or distribution) notify Genentech following any sale of Registrable
Securities under a Shelf Registration or distribution to the public pursuant to
Rule 144(k) (or any similar provision then in force, but not Rule 144A under the
Securities Act) and (iii) upon receipt of any notice from Genentech of the
happening of any event of the kind described in Section 4(c)(iii), 4(c)(iv),
4(c)(v) or 4(c)(vi) hereof, such holder will forthwith discontinue disposition
of such Registrable Securities covered by such Registration Statement or
Prospectus and will not resume disposition of such Registrable Securities until
such holder's receipt of the copies of the supplemented or amended Prospectus
contemplated by Section 4(k) hereof, or until it is advised in writing by
Genentech that the use of the applicable Prospectus may be resumed and has
received copies of the Registration Statement and Prospectus and any additional
or supplemental filings that are incorporated or deemed to be incorporated by
reference in such Prospectus.

      SECTION 5. Registration Expenses. Except as set forth in the next
succeeding sentence, Genentech shall pay the following fees and expenses
incurred by it incident to the performance of or compliance with this Agreement
by Genentech (i) all stock exchange fees, (ii) all internal expenses in
preparing or assisting in preparing, printing and distributing any Registration
Statement, any Prospectus, any amendments or supplements thereto, and other
documents relating to Genentech's performance of and compliance with this
Agreement, and (iii) all rating agency fees.
Notwithstanding the preceding sentence, Roche Holdings has separately agreed
with Genentech to pay (A) all reasonable external fees and expenses incurred by
Genentech, including, without limitations, reasonable fees and expenses of
counsel for Genentech, reasonable fees and expenses of independent public
accounts retained by Genentech (including the reasonable costs connected with
the delivery of any comfort letter) and printing expenses, (B) all SEC or
National Association of Securities Dealers, Inc. registration and filing fees
and (C) all filing fees in connection with compliance with state securities or
Blue Sky laws (the Purchaser and the Holders have no obligation


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to pay for such expenses outlined in clauses (A), (B) and (C)). Neither Roche
Holdings nor Genentech shall bear or reimburse the holders of Registrable
Securities and LYONs for any fees or expenses incurred by them, including,
without limitation, the fees and disbursements of the Special Counsel.

      SECTION 6. Indemnification; Contribution. (a) Indemnification by
Genentech. Genentech agrees to indemnify and hold harmless, to the fullest
extent permitted by law, each holder of Registrable Securities and each person
who controls any holder (within the meaning of either the Securities Act or the
Exchange Act) against any and all losses, claims, damages, liabilities and
expenses (including attorneys' fees) caused by any untrue or alleged untrue
statement of material fact contained in the Registration Statement, the
Prospectus or any preliminary prospectus (each as amended or supplemented, if
Genentech shall have furnished any amendments or supplements thereto), or any
omission or alleged omission to state therein a material fact required to be
stated therein or necessary to make the statements therein (in the case of a
prospectus, in the light of the circumstances under which they were made) not
misleading, provided that Genentech shall not be required to indemnify any
holder or controlling persons for any losses, claims, damages, liabilities or
expenses resulting from any such untrue statement or omission if such untrue
statement or omission is made in reliance on and conformity with any written
information with respect to such holder furnished to Genentech by such holder
expressly for use therein.

      (b) Indemnification by Holders. In connection with any Shelf Registration
in which a holder of Registrable Securities is participating, in furnishing
information relating to such holder of Registrable Securities to Genentech in
writing expressly for use in such Registration Statement, any preliminary
prospectus, the Prospectus or any amendments or supplements thereto, the holders
of such Registrable Securities agree, severally and not jointly, to indemnify
and hold harmless Genentech, any of its directors and officers who sign a
Registration Statement and each person, if any, who controls Genentech within
the meaning of either the Securities Act or the Exchange Act, to the same extent
as the foregoing indemnity from Genentech to such holder, but only with respect
to information relating to such holder furnished to Genentech in writing by such
holder expressly for use in the Registration Statement, or any amendment
thereto, or the Prospectus or any preliminary prospectus, or any amendment or
supplement thereto.

      (c) Conduct of Indemnification Proceedings. In case any proceeding
(including any governmental investigation) shall be instituted involving any
person in respect of which indemnity may be sought pursuant to Section 6(a) or
Section 6(b), such person (hereinafter called the indemnified party) shall
promptly notify the person against whom such indemnity may be sought
(hereinafter called the indemnifying party) in writing but failure to so notify
an indemnifying party shall not relieve such indemnifying party from any
liability hereunder to the extent it is not materially prejudiced as a result
thereof and in any event shall not relieve it from any liability which it may
have otherwise than on account of this indemnity agreement. The indemnifying
party, upon request of the indemnified party, shall retain counsel reasonably
satisfactory to the indemnified party to represent the indemnified party and any
others the indemnifying party may designate in such proceeding and shall pay the
fees and disbursements of such counsel related to such proceeding. In any such
proceeding, any indemnified party shall have the right to retain its own
counsel, but the fees and expenses of such counsel shall be at the expense of
such indemnified party unless (i) the


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indemnifying party and the indemnified party shall have mutually agreed to the
retention of such counsel, (ii) the indemnifying party has failed within a
reasonable time to retain counsel reasonably satisfactory to the indemnified
party, or (iii) the named parties to any such proceeding (including any
impleaded parties) include both the indemnifying party and the indemnified party
and the indemnified party shall have been advised by counsel that representation
of both parties by the same counsel would be inappropriate due to actual or
potential differing interests between them. It is understood that the
indemnifying party shall not, in respect of the legal expenses of any
indemnified party in connection with any proceeding or related proceedings in
the same jurisdiction, be liable for (a) the fees and expenses of more than one
separate firm (in addition to any local counsel) for Genentech, any of its
directors or officers who sign the Registration Statement and each person, if
any, who controls Genentech within the meaning of either the Securities Act or
the Exchange Act and (b) the fees and expenses of more than one separate firm
(in addition to any local counsel) for all holders of Registrable Securities and
all persons, if any, who control any holders of Registrable Securities within
the meaning of either the Securities Act or the Exchange Act, and that all such
fees and expenses shall be reimbursed as they are incurred. In such case
involving the holders of Registrable Securities and such controlling persons of
holders of Registrable Securities, such firm shall be designated in writing by
holders of a majority (with holders of LYONs deemed to be holders, for purposes
of determining such majority of the number of shares of Registrable Securities
into which such LYONs would be exchangeable as of the date such designation is
made) of shares of Registrable Securities. In all other cases, such firm shall
be designated in writing by Genentech.
The indemnifying party shall not be liable for any settlement of any proceeding
effected without its written consent, but if settled with such consent or if
there be a final judgment for the plaintiff, the indemnifying party agrees to
indemnify the indemnified party from and against any loss or liability by reason
of such settlement or judgment. Notwithstanding the foregoing sentence, if at
any time an indemnified party shall have requested an indemnifying party to
reimburse the indemnified party for fees and expenses of counsel as contemplated
by the third sentence of this section 6(c), the indemnifying party agrees that
it shall be liable for any settlement of any proceeding effected without its
written consent if (i) such settlement is entered into more than 30 days after
receipt by such indemnifying party of the aforesaid request and (ii) such
indemnifying party shall not have reimbursed the indemnified party in accordance
with such request or reasonably objected in writing, on the basis of the
standards set forth herein, to the propriety of such reimbursement prior to the
date of such settlement. No indemnifying party shall, without the prior written
consent of the indemnified party, effect any settlement of any pending or
threatened proceeding in respect of which any indemnified party is or could have
been a party and indemnity could have been sought hereunder by such indemnified
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.

      (d) Contribution. If the indemnification provided for in this Section 6
from the indemnifying party is unavailable to an indemnified party hereunder or
insufficient in respect of any losses, claims, damages, liabilities or expenses
referred to in this Section 6, then the 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, claims, damages,
liabilities or expenses in such proportion as is appropriate to reflect the
relative fault of the indemnifying party and indemnified parties in connection
with the actions which resulted in such losses, claims, damages, liabilities or
expenses, as well as any other relevant equitable considerations. The relative
fault of such


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indemnifying party and indemnified parties 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 to
state a material fact, has been made by, or relates to information supplied by,
such indemnifying party or indemnified parties, and the parties' relative
intent, knowledge, access to information and opportunity to correct or prevent
such action. The amount paid or payable by a party as a result of the losses,
claims, damages, liabilities and expenses referred to above shall be deemed to
include, subject to the limitations set forth in Section 6(c), any legal or
other fees or expenses reasonably incurred by such party in connection with any
investigation or proceeding.

      The parties hereto agree that it would not be just and equitable if
contribution pursuant to this Section 6(d) were determined by pro rata
allocation or by any other method of allocation which does not take into account
the equitable considerations referred to in the immediately preceding paragraph.
No person guilty of fraudulent misrepresentation (within the meaning of Section
11(f) of the Securities Act) shall be entitled to contribution from any person
who was not guilty of such fraudulent misrepresentation.

      If indemnification is available under this Section 6, the indemnifying
parties shall indemnify each indemnified party to the full extent provided in
Sections 6(a) and 6(b) without regard to the relative fault of said indemnifying
party or indemnified party or any other equitable consideration provided for in
this Section 6(d).

      Notwithstanding the provisions of this Section 6, no holder of Registrable
Securities 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 of Registrable Securities and distributed to the public were offered
to the public exceeds the amount of any damages that such holder of Registrable
Securities has otherwise been required to pay by reason of such untrue or
alleged untrue statement or omission or alleged omission.

      For purposes of this Section 6(d), each person, if any, who controls any
holder of Registrable Securities within the meaning of the Securities Act or the
Exchange Act shall have the same rights to contribution of such holder, and each
director or officer of Genentech who signed the Registration Statement, and each
person, if any, who controls Genentech within the meaning of the Securities Act
or the Exchange Act shall have the same rights to contribution as Genentech.

      SECTION 7. Rules 144 and 144a. Genentech shall use its reasonable efforts
to file the reports required to be filed by them under the Securities Act and
the Exchange Act in a timely manner and, if at any time it is not required to
file such reports but in the past had been required to or did file such reports,
it will, upon the request of any holder of Registrable Securities, make
available other information as required by, and so long as necessary to permit,
sales of its Registrable Securities pursuant to Rules 144 and 144A under the
Securities Act or, in each case, any similar rule or regulation hereafter
adopted by the SEC as a replacement thereto having substantially the same effect
as such rule. Notwithstanding the foregoing, nothing in this Section 7 shall be
deemed to require Genentech to register any of their securities pursuant to the
Exchange Act.


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      SECTION 8. Miscellaneous. (a) Remedies. In the event of a breach by
Genentech of any of its obligations under this Agreement, each holder of
Registrable Securities, in addition to being entitled to exercise all rights
granted by law, including recovery of damages, will be entitled to specific
performance of its rights under this Agreement. Genentech agrees that monetary
damages would not be adequate compensation for any loss 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 Inconsistent Agreements. Genentech shall not, on or after the date
of this Agreement, enter into any agreement with respect to their securities
that is inconsistent with the rights granted to the holders of Registrable
Securities in this Agreement or otherwise conflicts with the provisions hereof.

      (c) Amendments and Waivers. The provisions of this Agreement, including
the provisions of this sentence, may not be amended, modified or supplemented
(other than to cure any ambiguity or correct or supplement any provision
herein), and waivers or consents to departures from the provisions hereof may
not be given, unless Genentech has obtained the written consent of holders of a
majority of the shares of Registrable Securities (with holders of the LYONs
deemed to be the holders, for purposes of this Section, of the number of shares
of Registrable Securities into which such LYONs would be exchangeable as of the
date such consent is requested), except in the case of the Purchaser prior to
distribution of the LYONs to the holders, then the consent of the Purchaser.
Notwithstanding the foregoing, a waiver or consent to depart from the provisions
hereof with respect to a matter that relates exclusively to the rights of
holders of Registrable Securities whose securities are being sold pursuant to a
Registration Statement and that does not directly or indirectly affect the
rights of other holders of Registrable Securities or holders of LYONs may be
given by holders of at least a majority of shares of the Registrable Securities
being sold by such holders.

      (d) Notices. All notices and other communications provided for or
permitted hereunder shall be made in writing by hand-delivery, registered first
class mail, or telecopier:

          (i) if to a holder of Registrable Securities, at the most current
     address or telecopier number given by such holder to Genentech in
     accordance with the provisions of this Section 8(d) and Section 4, except
     with respect to the Purchaser prior to distribution of the LYONS, then to
     the Purchaser at the address set forth on the first page of the Purchase
     Agreement, attention of Andrew Burch (fax: 650-849-2102), with a copy to
     William Hinman, Shearman & Sterling, 555 California Street, San Francisco,
     CA 94104 (fax: (415) 616-1199);

          (ii) if to the Trustee or the Exchange Agent, 101 Barclay Street, New
     York, New York, attention: Corporate Trust Administrator (Fax: 212-
     815-5915), and thereafter by such other address, notice of which is given
     in accordance with the provision of this Section 8(d) by Roche Holdings,
     the Trustee or the Exchange Agent;

          (iii) if to Roche Holdings, Roche Holdings, Inc., One Commerce Center,
     Suite 1050, Wilmington, Delaware 19801, attention: Investor Relations (Fax:
     302-425-4713), and thereafter


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<PAGE>


     by such other address, notice of which is given in accordance with the
     provision of this Section 8(d);

          (iv) if to the Special Counsel, Shearman & Sterling, 555 California
     Street, San Francisco, CA 94104, attention: William Hinman (Fax:
     415-616-1199), and thereafter by such other address, notice of which is
     given in accorance with the provision of this Section 8(d); and

          (v) if to Genentech, Genentech, Inc., 1 DNA Way, South San Francisco,
     California 94080, attention: Corporate Secretary (fax: 650-225-8654), and
     thereafter by such other address, notice of which is given in accordance
     with the provision of this Section 8(d).

      All such notices and communications shall be deemed to have been duly
given: when delivered by hand, if personally delivered; five Business Days after
being deposited in the mail, postage prepaid, if mailed; the next Business Day
after being sent by next-day delivery by a solvent air courier; and when receipt
acknowledged, whether telecopied or otherwise (which acknowledgement may be via
electronic transmission, such as telecopier confirmation, e-mail receipt or
otherwise). All such notices and communications given in accordance with Section
8(d)(i) shall be deemed to have been duly given even if the last address or
telecopier number given by a holder of Registrable Securities pursuant to this
Section 8(d) and Section 4 is not current. Furthermore, a good faith effort made
by Genentech to give such notices and communications to holders of Registrable
Securities shall be deemed sufficient notice hereunder; provided that such
notices and communications shall have also been given to the Trustee and the
Exchange Agent.

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

      (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, including
without limitation and without the need for an express assignment, 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 an 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.

      (i) Severability. If any term, provision, covenant or restriction of this
Agreement is held by a court of competent jurisdiction to be invalid, 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 best efforts to


                                       12

<PAGE>



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 which may be hereafter declared
invalid, void or unenforceable.

      (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. 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 Genentech with respect to the
securities sold pursuant to the Purchase Agreement. This Agreement supersedes
all prior agreements and understandings between the parties with respect to such
subject matter.

      (k) Securities Held by Genentech or Roche Holdings or their Affiliates;
Calculation of Percentage of Registrable Securities. Whenever the consent or
approval of holders of a specified percentage of Registrable Securities is
required hereunder, any Registrable Securities and LYONs held by Genentech,
Roche Holdings or any of their affiliates shall not be counted in determining
whether such consent or approval was given by the holders of such required
percentage or amount.



                                       13

<PAGE>



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


                                       GENENTECH, INC.



                                       By    /s/ Stephen G. Juelsgaard
                                         ------------------------------
                                         Name:  Stephen G. Juelsgaard
                                         Title: Senior Vice President,
                                                General Counsel
                                                   and Secretary


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



                                       By    /s/ Andrew W. Burch
                                         ------------------------------
                                         Name:  Andrew W. Burch
                                         Title: Vice President



                                       14