Christiaan Neethling Barnard (8 November 1922 – 2 September 2001) 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 18 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.

Born in Beaufort West, Cape Province, Barnard studied medicine and practised for several years in his native South Africa. As a young doctor experimenting on dogs, Barnard developed a remedy for the infant defect of intestinal atresia. His technique saved the lives of ten babies in Cape Town and was adopted by surgeons in Britain and the United States. In 1955, he travelled to the United States and was initially assigned further gastrointestinal work by Owen Harding Wangensteen at the University of Minnesota. He was introduced to the heart-lung machine, and Barnard was allowed to transfer to the service run by open heart surgery pioneer Walt Lillehei. Upon returning to South Africa in 1958, Barnard was appointed head of the Department of Experimental Surgery at the Groote Schuur Hospital, Cape Town.

He retired as head of the Department of Cardiothoracic Surgery in Cape Town in 1983 after rheumatoid arthritis in his hands ended his surgical career. He became interested in anti-aging research, and in 1986 his reputation suffered when he promoted Glycel, an expensive "anti-aging" skin cream, whose approval was withdrawn by the United States Food and Drug Administration soon thereafter. During his remaining years, he established the Christiaan Barnard Foundation, dedicated to helping underprivileged children throughout the world. He died in 2001 at the age of 78 after an asthma attack.

Barnard was born on November 8, 1922 and grew up in Beaufort West, Cape Province, Union of South Africa. His father, Adam Barnard, was a minister in the Dutch Reformed Church. One of his four brothers, Abraham, was a "blue baby" who died of a heart problem at the age of three (Barnard would later guess that it was tetralogy of Fallot). The family also experienced the loss of a daughter who was stillborn and who had been the fraternal twin of Barnard's older brother Johannes, who was twelve years older than Christiaan. Barnard matriculated from the Beaufort West High School in 1940, and went to study medicine at the University of Cape Town Medical School, where he obtained his MB ChB in 1945.

His father served as a missionary to mixed-race people. His mother, the former Maria Elisabeth de Swart, instilled in the surviving brothers the belief that they could do anything they set their minds to.

Barnard did his internship and residency at the Groote Schuur Hospital in Cape Town, after which he worked as a general practitioner in Ceres, a rural town in the Cape Province. In 1951, he returned to Cape Town where he worked at the City Hospital as a Senior Resident Medical Officer, and in the Department of Medicine at Groote Schuur as a registrar. He completed his master's degree, receiving Master of Medicine in 1953 from the University of Cape Town. In the same year he obtained a doctorate in medicine (MD) from the same university for a dissertation titled "The treatment of tuberculous meningitis".

Soon after qualifying as a doctor, Barnard performed experiments on dogs while investigating intestinal atresia, congenital, life-threatening obstructions in the intestines. He followed a medical hunch that this was caused by inadequate blood flow to the fetus. After nine months and forty-three attempts, Barnard was able to reproduce this condition in a fetus puppy by tying off some of the blood supply to a puppy's intestines and then placing the animal back in the womb, after which it was born some two weeks later, with the condition of intestinal atresia. He was also able to cure the condition by removing the piece of intestine with inadequate blood supply. The mistake of previous surgeons had been attempting to reconnect ends of intestine which themselves still had inadequate blood supply. To be successful, it was typically necessary to remove between 15 and 20 centimeters of intestine (6 to 8 inches). Jannie Louw used this innovation in a clinical setting, and Barnard's method saved the lives of ten babies in Cape Town. This technique was also adapted by surgeons in Britain and the US. In addition, Barnard analyzed 259 cases of tubercular meningitis.

Owen Wangensteen at the University of Minnesota in the United States had been impressed by the work of Alan Thal, a young South African doctor working in Minnesota. Wangensteen asked the Groote Schuur Head of Medicine John Brock if he might recommend any similarly talented South Africans, and Brock recommended Barnard. In December 1955, Barnard travelled to Minneapolis, Minnesota to begin a two-year scholarship under Chief of Surgery Wangensteen, who assigned Barnard more work on the intestines, which Barnard accepted even though he wanted to move onto something new. Simply by luck, whenever Barnard needed a break from this work, he could wander across the hall and talk with Vince Gott who ran the lab for open-heart surgery pioneer Walt Lillehei. Gott had begun to develop a technique of running blood backwards through the veins of the heart so Lillehei could more easily operate on the aortic valve (McRae writes, "It was the type of inspired thinking that entranced Barnard"). In March 1956, Gott asked Barnard to help him run the heart-lung machine for an operation. Shortly thereafter, Wangensteen agreed to let Barnard switch to Lillehei's service. It was during this time that Barnard became acquainted with fellow future heart transplantation surgeon Norman Shumway. Barnard also became friendly with Gil Campbell, who had demonstrated that a dog's lung could be used to oxygenate blood during open-heart surgery. (The year before Barnard arrived, Lillehei and Campbell had used this procedure for twenty minutes during surgery on a 13-year-old boy with ventricular septal defect, and the boy had made a full recovery.) Barnard and Campbell met regularly for early breakfast. In 1958, Barnard received a Master of Science in Surgery for a thesis titled "The aortic valve – problems in the fabrication and testing of a prosthetic valve". The same year he was awarded a Ph.D. for his dissertation titled "The aetiology of congenital intestinal atresia". Barnard described the two years he spent in the United States as "the most fascinating time in my life."^{[citation needed]}