Stewart Cowen was born at Eaglehawk in Victoria. His father, Herbert Osburn Cowen, hailed from the Isle of Man, as did his uncle, Barwick Stewart Cowen. Both graduated in medicine at Glasgow, and migrated to Victoria. His father practised in Eaglehawk and later for many years in Kew, a busy and highly esteemed family doctor, who nevertheless found time to read several papers on puerperal fever at professional meetings.

Stewart was educated at Melbourne Grammar School, where he succeeded both scholastically and at sport. At an early age he qualified for entrance to the University, but his father insisted he spend two years `acquiring the basis of a sound education'; in fact, studying English and history. Stewart became a fluid and lucid lecturer as well as an entertaining raconteur and companion.

Stewart Cowen entered the University of Melbourne in 1911. In October, 1914, he enlisted in the AIF, and was a hospital sergeant at Lemnos, but was sent back to complete his medical course in 1915. He maintained his high academic standard finishing in first place in all three final year subjects - medicine, surgery and obstetrics and gynaecology. On graduating in 1916 he rejoined the AIF in France, serving with distinction until the armistice.

On return to Melbourne in 1919 he entered consultant practice, and was appointed physician to outpatients at the Royal Melbourne Hospital in 1923, succeeding to a senior post in 1928. Here he was renowned as a clinician and a teacher. Because of his clarity of thought and his command of the English language his lectures and clinics were never dull. He was appointed Stewart Lecturer in Medicine in 1937, which was the senior appointment before there was a professor at the University. He retired from the Hospital in 1945. Stewart Cowen was one of the founding fathers of the College and assumed the onerous task of being its first censor-in-chief, 1938 to May 1945. He set a high standard, was fair and just, and at all times courteous and considerate. His wisdom and ability ensured that the Membership of the College would be accepted on a basis of equality by the older colleges. He was an elected councillor 1945-46 and vice- president in 1946. His early and sudden death in November 1946 prevented him succeeding to the highest office in the College.

Stewart Cowen married Frances Madge Hillicrest in November 1918, and they had three daughters.