In 1943, Bristol-Myers bought Cheplin Laboratoriesﾗa Syracuse, New York, manufacturer of acidophilus milkﾗand broke ground for a new penicillin plant.

Cheplin became a key supplier of penicillin for the Allied armed forces during World War II. After the war it was clear that penicillin and other antibiotics were an immense opportunity for Bristol-Myers. Cheplin was renamed Bristol Laboratories in 1945 and Frederic N. Schwartz was put in charge.