Donald Stewart McKenzie was born in Douglas, Lanarkshire, on 12 September 1912 to John Chancellor McKenzie and his wife, Ella, née Scott. His father was in general practice, his uncle, Dan McKenzie, a Fellow of the Edinburgh College, his cousin William Stewart McKenzie FRCS (see *Lives of the Fellows*, 1974-82, p.25), and his son Neil Stewart McKenzie became a medical practitioner. He was educated at Edinburgh Academy and the University of Edinburgh. His initial resident appointments were at Leith Hospital and Edinburgh Infirmary, where he worked under Sir Walter Mercer, and later at Chester Royal Infirmary. During the second world war he served in the RAMC, with the rank of Major, from 1941 to 1946. While in India he became interested in amputees and artificial limbs and founded the limb fitting centre in Poona which was still in operation forty years later. On leaving the army he joined the staff of the limb fitting centre at Roehampton where he became senior medical officer and director of the Ministry of Health research unit. In 1968 the DHSS opened its Biochemical Research and Development Unit at Roehampton and McKenzie was appointed the first director and promoted to principal medical officer. In 1972 he was elected a Fellow of the College. He was appointed honorary limb fitting consultant to Chailey Heritage, the Westminster Hospital and Queen Mary's Hospital, Roehampton. Through his support of the International Society for Prosthetics and Orthotics and as a Fellow of the British Orthopaedic Association he became a world authority and teacher in his specialty. In 1961 the French Ministre des Anciens Combattants decorated him with the Croix de Mérite Combattants Chevalier. He married in 1947 Kay Sealy, daughter of a Colonel in the RAMC, and they had four children, Neil, Alison, Katrine and Hamish. He died peacefully at his home in Surrey on 29 January 1984 aged 71 years, survived by his wife and family.