Frank Ritchie was the only son of Harold John Ritchie, distinguished physician on the staff of Sydney Hospital and President of the Australian College of Physicians from 1944 to 1946, and his wife Elizabeth Jane nee Swift.

His early education was at Tudor House and Geelong Grammer School. He was a clinical student at Sydney Hospital and graduated in 1943 from Sydney University. He was, for a time, RMO Sydney Hospital then joining the Armed Forces serving 2/12 Field Ambulance, 2/17 Australian Infantry Battalion and the 113th AGH. Upon demobilization he studied at John Hopkins Hospital, Baltimore, USA as a Nuffield travelling fellow. On his return to Sydney he entered private practice as a consultant physician in Macquarie Street and was appointed to the staff of Sydney Hospital and St Luke's Hospital. In 1947 he married Mary Elizabeth, daughter of farmer Brian Tainton, and had one son and two daughters. The marriage was dissolved in 1972. He remarried Joyce Gaskell in 1975.

As a clinical tutor at Sydney Hospital his classes were eagerly attended. He joined a band of "junior" physicians who were employing the evolving science of medicine to the time-honoured bedside teaching. His teaching skills called upon his students to copy his precise analysis of diagnosis, therapy and prognosis, but in each instance highly personalised to the person who was ill. He was pressured to follow an academic pathway but declined, preferring the personal contact of bedside medicine. Frank was not actively engaged in clinical research but had published articles on thyroid disease and the use of the electrocardiogram. He was dynamic in encouraging the research activities of his colleagues.

His skills as an administrator and negotiator for his beloved Sydney Hospital called him to serve on the board of Sydney Hospital, being vice-president from 1962 to 1968 and president from 1968 until his death in 1982. During these years he was unswerving in his belief in Sydney Hospital as an institution of excellence. He furthered its research objectives by inaugurating the research foundation of 1978.

Outside the field of medicine, he was the chairman of the board of National Mutual Life Association of Australia and chairman of the Intercommercial Properties Pty. He had the remarkable ability to simplify complex issues, medical or political, and to use the English language in simple direct phrases which allowed no ambiguity. In his role as a caring physician, he was able to carry hope and comfort by his voice and attitude of distinguished understanding. He was much loved by his patients. His recreation was his love of the sea and big game fishing and the adventure involved therein, at one time leading him as far north as Cape York. The medical world lost prematurely an outstanding man of vision; his friends lost a large part of themselves; his record speaks for itself.