Richard Brownell Brenan read medicine at Trinity College, Dublin, and qualified in 1942. After serving as a Surgeon-Lieutenant in the RNVR he passed the FRCSI in 1947, obtained the FRCS in 1956 and spent some time as surgical registrar at the Royal Northern Hospital and as surgeon at the Nairobi General Hospital in Kenya. Returning to Dublin he became assistant surgeon at the Adelaide Hospital and Royal City of Dublin Hospital. After gaining the MCh degree in 1960 he became surgeon to Mercer's Hospital and the Royal City of Dublin Hospital and later added to these posts in Dublin those of honorary consulting surgeon to the Royal Victoria Eye and Ear Hospital and the Royal Hospital at Donnybrook.