Mahapitiyage Peiris was born in Panadura, Ceylon, on 28 July 1898, the son of M A Peiris, a merchant, and was educated at St John's School, Panadura, and St Joseph's College, Colombo, before entering Ceylon Medical College qualifying in 1926.After graduation and junior hospital posts he was appointed lecturer in anatomy and later lecturer in surgery at Ceylon Medical College passing the FRCS in 1929. He served in the Ceylon Medical Corps from 1930 to 1945 acting as surgeon to the Military Hospital in Ceylon. His interests were in both general and orthopaedic surgery and during his early years on the staff of the hospital, laboratory services were meagre, spinal anaesthesia was most commonly performed, and he often administered this personally before proceeding with the operation. He served on the staff of the General Hospital, Colombo, from 1936 to 1960, was President of the Ceylon Medical Association in 1954 and also a member of the Council of Ceylon University. In later years he became a cabinet minister, a senator and a diplomat. He married Edith Carey in 1945 and had three sons and one daughter who graduated in medicine from the University of Ceylon. He died on 26 April 1988 at the age of 89.