Exhibit 31.1
CERTIFICATIONS
I, Clay B. Siegall, certify that:
| 1. | I have reviewed this Amendment No. 1 to the Quarterly Report on Form10-Q/A of Seattle Genetics, Inc.; 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. |
Date: September 15, 2017
/s/ Clay B. Siegall |
Clay B. Siegall Chief Executive Officer (Principal Executive Officer) |