The son of an Irish country surgeon who had been a pupil of John Abernethy. He entered St Bartholomew's Hospital in October, 1816, and was for twenty years Surgeon to the Finsbury Dispensary, and temporarily to the Fever Hospital. He was also Consulting Surgeon to St Anne's Society Schools and to the City of London Truss Society. He lived in the Court Yard, Albany, Piccadilly, from 1853-1871, when he gave up his chambers and retired to Matching, near Harlow, Essex, where he died on January 22nd, 1882. MacIlwaine was an uncompromising foe to vivisection, publishing papers on the subject in 1843, 1847, and 1877, but he is now best remembered by his *Memoirs of John Abernethy*, of which the first and second editions appeared in two volumes in 1853, the third, in one volume, with considerable additions, in 1856. His photograph hangs in the office of the City of London Truss Society. Publications: "On Vivisection." - *Lond Med Gaz*, 1843, xxxii, 847. *Remarks on Vivisection*, 8vo, London, 1847. *Vivisection*, 8vo, London, 1877.