Bob Kenihan was born in Adelaide, South Australia, on 1 February 1923, the son of Raphael Kenihan, a family medical practitioner. He attended Rostrevor College for his secondary schooling, before entering the University of Adelaide Medical School, from which he graduated in 1946. During this time, he excelled at sport, gaining a university Blue in lacrosse, as well as being proficient in cricket, swimming and golf.
After internship at the Royal Adelaide Hospital, he served in the Royal Australian Army Medical Corps (RAAMC) as a member of the British Commonwealth Occupation Force in Japan from 1948 to 1949. This was the beginning of his long association with the RAAMC as a serving member of the Citizen Military Forces, in which he held senior positions in 3 Field Ambulance from 1949 to 1967. He was duly recognised with the award of the Efficiency Decoration and clasp for his meritorious service.
