LIMITED POWER OF ATTORNEY
FOR SECTION 16 REPORTING OBLIGATIONS

Know all of these presents, that the undersigned hereby
revokes and nullifies any prior power of attorney for Section
16 reporting obligations, and makes, constitutes and appoints
each of Laurie Keating, Jeffrey Poulton, Mary Beth DeLena and
Cindy Anderson, signing singly and each acting individually,
as the undersigneds true and lawful attorney-in-fact with full
power and authority as hereinafter described to:

(1) execute for and on behalf of the undersigned, in the
Undersigneds capacity as an officer and/or director of Alnylam
Pharmaceuticals, Inc. (the Company), Forms 3, 4 and 5
(including any amendments thereto) in accordance with Section
16(a) of the Securities and Exchange Act of 1934, as amended,
and the rules thereunder (the Exchange Act);

(2) do and perform any and all acts for and on behalf of the
undersigned which may be necessary or desirable to prepare,
complete and execute any such Form 3, 4, or 5, prepare, complete
and execute any amendment or amendments thereto, and timely
deliver and file such form with the United States Security and
Exchange Commission and any stock exchange or similar authority;

(3) seek or obtain, as the undersigneds representative and on
the undersigneds behalf, information regarding transactions in
the Companys securities from any third party, including
brokers, employee benefit plan administrators and trustees, and
the undersigned herby authorizes any such person to release any
such information to such attorney-in-fact and approves and
ratifies any such release of information; and

(4) take any other action of any type whatsoever in connection
with the foregoing which, in the opinion of such attorney-in-
fact, may be of benefit to, in the interest of, or legally
required by, the undersigned, it being understood that the
documents executed by such attorney-in-fact on behalf of the
undersigned pursuant to this Power of Attorney shall be in such
form and shall contain such terms and conditions as such
attorney-in-fact may approve in such attorney-in-facts
discretion.

The undersigned herby grants to each such attorney-in-fact full
power and authority to do and perform any and every act and
thing whatsoever requisite, necessary, or proper to be done in
the exercise of any of the rights and powers herein granted, as
fully to all intents and purposes as to the undersigned might or
could do of personally present, with full power of substitution
or revocation, hereby ratifying and confirming all that such
attorney-in-fact or such attorney-in-facts substitute or
substitutes, shall lawfully do or cause to be done by virtue of
this power of attorney and the rights and powers herein granted.
The undersigned acknowledges that the foregoing attorneys-in-
fact, in serving in such capacity at the request of the
undersigned, are not assuming nor relieving, nor is the Company
assuming nor relieving, any of the undersigneds
responsibilities to comply with Section 16 of the Exchange Act.
The undersigned Acknowledges that neither the company nor the
foregoing attorneys-in-fact assume (i) any liability of the
undersigneds responsibility to comply with the requirements of
the Exchange Act, (ii) any liability of the undersigned for any
failure to comply with such requirements, or (iii) any
obligation or liability of the undersigned for profit
disgorgement under Section 16(b) of the Exchange Act.

This Power of Attorney shall remain in full force and effect
until the undersigned is no longer required to file Forms 3, 4,
and 5 with respect to the undersigneds holdings of and
transactions in securities issued by the Company, unless earlier
revoked by the undersigned in a signed writing delivered to the
foregoing attorneys-in-fact.

IN WITNESS WHEROF, the undersigned has caused this Power of
Attorney to be executed as of this 25th day of February, 2020.

Barry Greene
Print Name

/s/ Barry Greene
Signature