Exhibit 24

                               POWER OF ATTORNEY

     KNOW ALL BY THESE PRESENTS, that the undersigned hereby constitutes and
appoints each of Robert Coffin, Philip Astley-Sparke and Jean Franchi, signing
singly, as his true and lawful attorney-in-fact to:

        (1)  execute for and on behalf of the undersigned, in the undersigned's
     capacity as a director of Replimune Group, Inc. (the "Company"), Forms 3,
     4, and 5 in accordance with Section 16(a) of the Securities Exchange Act of
     1934 and the rules thereunder and any other forms or reports the
     undersigned may be required to file in connection with the undersigned's
     ownership, acquisition, or disposition of securities of the Company;

        (2)  do and perform any and all acts for and on behalf of the
     undersigned which may be necessary or desirable to complete and execute any
     such Form 3, 4, or 5, or other form or report, and timely file such form or
     report with the U.S. Securities and Exchange Commission and any stock
     exchange or similar authority; and

        (3)  take any other action of any type whatsoever in connection with
     the foregoing which, in the opinion of such attorneys-in-fact, may be of
     benefit to, in the best interest of, or legally required by, the
     undersigned, it being understood that the documents executed by such
     attorneys-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 attorneys-in-fact may approve in his discretion.

     The undersigned hereby grants to each such attorney-in-fact full power and
authority to do and perform each and every act and thing whatsoever requisite,
necessary, and proper to be done in the exercise of any of the rights and powers
herein granted, as fully to all intents and purposes as the undersigned might or
could do if personally present, with full power of substitution or revocation,
hereby ratifying and confirming all that such attorneys-in-fact, or his
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 no such attorneys-in-fact, in serving in such
capacity at the request of the undersigned, is hereby assuming any of the
undersigned's responsibilities to comply with Section 13 and Section 16 of the
Securities Exchange Act of 1934 and the rules thereunder, as amended.

     This Power of Attorney amends and restates in its entirety the Power of
Attorney that the undersigned previously signed and delivered in connection with
the undersigned's ownership, acquisition, or disposition of securities of the
Company.

     This Power of Attorney shall remain in full force and effect until revoked
by the undersigned in a signed writing delivered to the foregoing attorneys-in-
fact.

                            [Signature Page Follows]


     IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 31 day of March, 2020.


                                 /s/ Otello Stampacchia
                                 ------------------------------
                                 Otello Stampacchia