Robert Guerin was born in Adelaide on 8 July 1932. His father, Robert Guerin, and mother, Vera Jean née Langley, were both schoolteachers. He was educated at Adelaide High School, where he won numerous prizes and became head prefect. He qualified with credit, winning the gynaecology prize, from the University of Adelaide in 1957. After being house surgeon at the Royal Adelaide and the Adelaide Children's Hospital, he did six years in general practice, before returning to the Royal Adelaide Hospital to train as a surgeon, soon deciding to specialise in ENT. He went to London to be a registrar in ENT at St Mary's, and later senior house officer in ENT at the Radcliffe Infirmary in Oxford, being promoted to registrar in 1968. Having passed the Edinburgh and English Fellowships, he returned to Adelaide in 1970, as registrar at the Adelaide Children's Hospital. He was appointed visiting medical officer there, and to the Repatriation General Hospital in 1971, with the appointment as clinical lecturer in otology at the University of Adelaide and, in the following year, to Flinders University. He was an external examiner at the University of Papua, New Guinea, in 1995. He published papers on hypophysectomy and the treatment of recurrent tracheo-oesophageal fistula by means of a sternomastoid flap. He married Naomi Heather née Schultz in 1960. They had one son, Robert Alfred, and one daughter, Frances, who became a university lecturer. He died on 24 October 1999.