G. H. Choa was a Lecturer in Medicine at the University of Hong Kong in 1949-1956, Consultant Physician at the Queen Mary Hospital in 1956-1967, then Deputy Director and Director of Medical and Health Service, Hong Kong Government in 1967-1977, and the Founding Dean of the Faculty of Medicine, The Chinese University of Hong Kong in 1978-1988. He is also the author of ""Heal the Sick" Was Their Motto: The Protestant Medical Missionaries in China," which is a history of medical education in China.