Born on 5 April 1899 at Culloden, Georgia, USA, son of George Zadock Blalock, a merchant and Martha Davis his wife, he was educated at the University of Georgia, Athens, USA and at the Johns Hopkins University and Hospital, Baltimore, where he was resident assistant surgeon 1922-25. He then went to Nashville, Tennessee as resident surgeon at Vanderbilt University Hospital, becoming surgeon and Professor of Surgery 1938-41. Blalock returned to Johns Hopkins in 1941 as surgeon-in-chief and Professor of Surgery, a prize position in academic surgery, and held these posts till his retirement in 1964. He was chairman of the Medical Board of the University and Hospital 1955-64. He had made his mark at Vanderbilt by his use of Hunter's method of physiological research as a basis for surgical advance, and by his success as a teacher of young surgeons. He was also in the forefront of the campaign against shock which was being actively pursued by leading surgeons at that time, and published an influential book *Principles of surgical Care: Shock and other problems* (St Louis, Mosby, 1940; 325 pages). At Johns Hopkins he was particularly notable for his choice of able pupils and the number of young professors whom his training produced. He kept up his own researches as well as his clinical work, and promoted the welfare and progress of his department and the Hospital and University in general. He began to work with a team of able collaborators on malformations and deficiency of the heart, and with Dr Helen Taussig he announced in the *Journal of the American Medical Association* on 19 May 1945 (vol 128, p 189) the successful surgical relief of the disabilities which arise from pulmonary stenosis, usually called "Fallot's tetralogy". His operation of systemic-pulmonary anastomosis to by-pass the stenotic area demonstrated the value of this surgical intervention, explained the physiological basis of his method by showing that the restoration of adequate blood-supply to the lungs removed the symptoms of the disease, and inspired and stimulated the development of cardiac surgery. Blalock's work was acclaimed and followed all over the world. He became in great demand as a lecturer at home and abroad. He was elected to the Académie de Chirurgie in Paris in 1946 and a Chevalier of the Legion of Honour of France in 1947. Also in 1947 he was invited to work at Guy's Hospital as honorary consulting surgeon, while his lectures at the British Medical Association and the Royal College of Surgeons were welcomed with enthusiasm by unprecedentedly large audiences, and he was elected an Honorary Fellow of the College. In the next eight years he received honorary degrees from nine universities and honorary Fellowships from the principal medical institutions of many countries. At home, among many other honours, he was chosen President of the chief surgical societies, eg Society for Clinical Surgery and American Association for Thoracic Surgery 1950, Society for Vascular Surgery 1951, American College of Surgeons 1954, American Surgical Association 1956. He was a founder of the American Board of Surgery, and in 1951 a Blalock Society was formed in his honour. He came again officially to England in 1954, when a clinical meeting of the American College of Surgeons inaugurated the restored building of the Royal College, and again gave a most inspiring lecture. He was a prolific writer on surgery and physiology, his bibliography numbering 228 papers, which were republished in two massive volumes after his death. Blalock married twice: in 1930 Mary Chambers O'Bryan, who died in December 1958 leaving two sons and a daughter; secondly, in 1959, Alice Seney Waters, who survived him; his mother also outlived him. He was a simple, direct and charming man, who retained a youthful vitality and drive into middle life, but his health suddenly failed in his early sixties and three months after retiring he died on 15 September 1964. Publications: Operations performed and vascular anomalies encountered in the treatment of congenital pulmonic stenosis. (Moynihan lecture). *Ann Roy Coll Surg Engl* 1948, 3, 57. The expanding scope of cardio-vascular surgery (Moynihan lecture). *Brit J Surg* 1954, 42, 225. *The Papers of Alfred Blalock* edited by Mark M Ravitch. Baltimore, Johns Hopkins Press, 1966. 2 volumes, 2026 pages, including a memoir, list of honours, bibliography, portraits etc.