Exhibit 99.1 Repligen Corporation 41 Seyon Street Building #1, Suite 100 Waltham, Massachusetts 02453 Repligen Reports Fourth Quarter and Full Year 2023 Financial Results • Reports fourth quarter revenue of $156 million and full year revenue of$639 million • Continued strength in orders with fourth quarter book-to-bill ratio of 1.03 WALTHAM, Mass., February 21, 2024 — Repligen Corporation (NASDAQ:RGEN), a life sciences company focused on bioprocessing technology leadership, today reported financial results ...