Born on 14 December 1872, the son of Axel Key, professor of pathological anatomy at the Royal Caroline Institute, Stockholm, he was partly of Scottish descent. Key graduated in 1907 and served from 1911 to 1937 as surgeon to the Maria Hospital, Stockholm, and was appointed also professor of surgery at the Royal Caroline Institute in 1923. With Gosta Forsell he founded and built in 1931 the Caroline Hospital (Karolinska Sjukhus). From 1919 he edited the premier Scandinavian surgical journal, the *Acta Chirurgica Scandinavica*, which superseded the *Nordisk Medicinisk Arkiv*, formerly edited by his father. At the height of his career Einar Key was the leading surgeon in the North, and was particularly well-known in Great Britain. He was elected a corresponding member of the British Medical Association in 1949. The *British Medical Journal* commemorated his eightieth birthday with a special article. He died in Stockholm on 11 August 1954, aged 81.