EXHIBIT 31.1

I, Scott Koenig, certify that:

1.I have reviewed this Amendment No. 1 to the Annual Report on Form 10-K of MacroGenics, Inc. (this “Report”); and

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this Report.

/s/ Scott Koenig

Scott Koenig, M.D., Ph.D.

President and Chief Executive Officer

(Principal Executive Officer)

Date: March 2, 2020