During World War II, the Wellcome Research Laboratories in Tuckahoe, New York hired Elion as a biochemist. In 1988, she and her colleague, George Herbert Hitchings, received the Nobel Prize in Physiology or Medicine. They both discovered and developed treatments for previously incurable diseases. Some of those diseases were leukemia and herpes. She became the senior research chemist. Later, she was promoted to the head of the Department of Experimental Therapy.