Kenneth Rees-Thomas was the son of Arthur, an accountant in Roseneath, New Zealand, and his wife Edith Amy, née Heal. He was educated at Roseneath Primary School and then at Wellington College. On leaving school he trained and qualified as a pharmacist, but then on the advice of a family medical friend he decided to seek a career in medicine. He got a place in the Otago Medical School, from which he qualified in 1934. After completing junior appointments in Wellington and Newtown he decided upon a career in surgery and sailed for London in January 1937. In May of that year he passed his primary Fellowship and then worked at the West London Hospital, Guy's, and St Peter's Hospital for Stone, passing his final Fellowship in 1939. Returning to Wellington at the end of 1939 he combined general practice and surgery until 1941, when he joined the army, serving with the 3rd Division Ambulance of the 4th General Hospital and 2nd Field Surgical Unit in New Caledonia with the rank of major. In 1948 he was appointed assistant surgeon to Wellington Hospital and also became FRACS in that year. In 1958 he became senior surgeon, finally retiring ten years later. In addition to this respected surgical career he had been adviser to the health department in Wellington and adviser on the pharmacology and therapeutics committee there for twenty years. Following retirement he continued his longstanding interest in musculoskeletal medicine by continuing in practice using osteopathic techniques. Outside his professional work he was active in the Baptist Church and President of the Christian Businessmen's Association, as well as the Wellington Marriage Guidance Council. Enjoying the outdoor life, he was a keen fisherman and skier. He married Irene Kent in 1938 and she pre-deceased him, as did a second son with Hodgkin's disease. He died on 26 March 1992, survived by two sons.