Born at Cartwright, Durham County, Ontario, Canada, on 25 May 1877, the son of Nelson Marlow and Ann Parr, his wife. He was educated at Port Perry and took honours at Trinity Medical College, Toronto, in 1900. He served for a year as house surgeon at St Michael's Hospital, and then proceeded to London, where he studied at University College, Middlesex, and King's College Hospitals. Returning to Toronto, he was appointed assistant surgeon at St Michael's Hospital in 1904, became surgical registrar at the Toronto General Hospital and was attached to the gynaecological service, then under Professor J F W Ross, until 1911. Two years later (1913) he was appointed associate professor of gynaecology in the University of Toronto, and he became the senior attending gynaecologist at the Toronto General Hospital. He was also on the staff of the Wellesley Hospital and of St John's Hospital. During 1903-06 he was demonstrator of anatomy in the University of Toronto. In 1913 he became a founding Fellow of the American College of Surgeons; in 1919 he was president of the Ontario Medical Association, and in 1928 he was elected president of the Toronto Academy of Medicine. Marlow joined the Canadian Army Medical Corps as a private when it was organized in 1900 and rose to the rank of lieutenant-colonel. During the war he was ADMS for military district No 2, and was Inspecting Officer of the CAMC throughout Canada. He married in 1903 Florence Elizabeth Walton of Thorold. She survived him but without children, as their daughter had died in 1916. During the last two years of his life Marlow busied himself with a farm. He died suddenly on 22 August 1936 and was buried, after a largely-attended funeral service, at St Paul's Church, Toronto. He is described as a man of commanding presence, keen, forceful, an indefatigable worker, a ready speaker, and of pleasing personality.