Edward Donnall Thomas was an American physician and professor of Medicine who did pioneer research on bone marrow transplant which proved to be a milestone in treating leukemia and other blood disorder related fatal diseases. He was honored with the prestigious Nobel Prize in Physiology or medicine in 1990. He began his research in 1950s when bone marrow transplant was a dismissed idea. However, his persistent efforts and groundbreaking research is responsible for saving the lives of thousands of people around the globe. Bone marrow transplantation and its allied therapies, like blood stem cell transplantation have proved an important milestone in medical science.