Pat O'Donnell was born at Myrtleford, north-eastern Victoria, and spent his childhood in that area. His father was a popular local grazier with a large family, and Pat was the youngest of eight children. He attended Wesley College, Melbourne, as a boarder, and graduated MB BS with honours from University of Melbourne in 1939.

Two of his sisters became nurses and his eldest brother, Ken, a physician (MD FRACP) practised in Hamilton, Victoria. The youngest sister, Alice Margaret, died when the hospital ship Centaur was destroyed by enemy action off the Australian coast on 14 May 1943.

Pat excelled at cricket and tennis at school and university. He was later a member of the Kooyong Tennis Club in Melbourne, as well as the MCC. He was an ardent Melbourne Football Club fan. Following his graduation he completed a residency at Royal Melbourne Hospital, before joining the AAMC. He was first attached to 2/10 AGH as a general duties medical officer. He became a prisoner of war with the fall of Singapore in February, 1942. In company with a largely British Army contingent, he was transported to a Japanese internment camp in Taiwan, where he spent the rest of the War.

Pat rarely spoke of his experiences during this period, but starvation and physical hardship were the lot of this group. A sad memory was of relief stores, parachuted onto the camp at the end of the War, killing two of his fellow-prisoners. He spoke of learning for the first time of the new wonder drug penicillin, parachuted without instruction on its medical properties or use.

On return to civilian life, Pat held a succession of medical administrative posts, assistant medical superintendent, Royal Melbourne Hospital 1946-51, and medical superintendent Dunedin Hospital, NZ 1951-54, and Royal Melbourne Hospital 1954-64. On May 11 1951 he married Marjorie Marshall, who provided a happy home and wonderful support through the years. They had two children who enjoyed the greatest love and companionship in their family life.

In 1964 he came to his final post as general medical superintendent of Canberra Hospital. This was a time of great medical activity in Canberra, when much of the work involved in building a new hospital and reorganising the local medical facilities fell to Pat. His splendid administrative skill, combined with a warm, approachable personality, defused many an explosive situation in those difficult times. Well aware of the nature of his final illness, Pat planned his farewell with predictable courage and dignity, and without complaint.