Christiaan Neethling Barnard was a South African cardiac surgeon who performed the world's first human-to-human heart transplant operation. On 3 December 1967, Barnard transplanted the heart of accident victim Denise Darvall into the chest of 54-year-old Louis Washkansky who regained full consciousness and was able to talk easily with his wife, before dying eighteen days later of pneumonia, largely brought on by the anti-rejection drugs that suppressed his immune system. Barnard had told Mr. and Mrs. Washkansky that the operation had an 80% chance of success, an assessment which has been criticised as misleading. Barnard's second transplant patient, Philip Blaiberg, whose operation was performed at the beginning of 1968, returned home from the hospital and lived for a year and a half.

Vladimir Petrovich Demikhov was a Soviet Russian scientist and organ transplantation pioneer, who performed several transplants in the 1940s and 1950s, including the transplantation of a heart into an animal and a heart–lung replacement in an animal. He is also well known for his dog head transplants, which he conducted during the 1950s, resulting in two-headed dogs. This ultimately led to the head transplants in monkeys by Robert White, who was inspired by Demikhov's work.