Exhibit 24

                               POWER OF ATTORNEY

     The undersigned, as a Section 16 reporting person of ALX Oncology Holdings
Inc. (the "Company"), hereby constitutes and appoints Jaume Pons and Peter
Garcia, and each of them, as the undersigned's true and lawful attorney-in-fact
to:

     1.    complete and execute Forms 3, 4 and 5 and other forms and all
           amendments thereto as such attorney-in-fact shall in his discretion
           determine to be required or advisable pursuant to Section 16 of the
           Securities Exchange Act of 1934 (as amended) and the rules and
           regulations promulgated thereunder, or any successor laws and
           regulations, as a consequence of the undersigned's ownership,
           acquisition or disposition of securities of the Company; and

     2.    do all acts necessary in order to file such forms with the SEC, any
           securities exchange or national association, the Company and such
           other person or agency as the attorneys-in-fact shall deem
           appropriate.

      The undersigned hereby ratifies and confirms all that said attorneys-in-
fact and agents shall do or cause to be done by virtue hereof.  The undersigned
acknowledges that the foregoing attorneys-in-fact, in serving in such capacity
at the request of the undersigned, are not assuming, nor is the Company
assuming, any of the undersigned's responsibilities to comply with Section 16 of
the Securities Exchange Act of 1934 (as amended).

       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
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to the
Company and the foregoing attorneys-in-fact.

      IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to
be executed as of this 15th day of April, 2021.


                                Signature: /s/ Shelly Pinto
                                           --------------------------------
                                Print Name: Shelly Pinto