After working as a house surgeon at Middlesex Hospital he returned to New Zealand in 1891.[1] In 1890 he was the first New Zealander to be made a fellow of the Royal College of Surgeons.[1]
Following locum surgical positions at Dunedin Hospital and temporary lectureships at the University of Otago Medical School he became a full lecturer in 1899 and professor of surgery from 1909 until 1924.[1]
Barnett researched the potentially fatal hydatid disease (see echinococcus) at the University and established the hydatid registry of the College of Surgeons.[1] He spent time investigating the disease with Félix Dévé, a French authority on the hydatid parasite, in 1926.[1]
Barnett established a reputation for safe and sound surgery, particularly aseptic principles.[1] He was the first surgeon in New Zealand to wear rubber gloves and a gauze mask in the operating theatre.[1] From 1920 he was instrumental in establishing a professional body for surgeons to raise the standard of surgery. In 1926 the College of Surgeons of Australasia (later the Royal Australasian College of Surgeons) was founded and Barnett served as president from 1937 to 1939.[1]
On his retirement Barnett endowed the Ralph Barnett Chair in Surgery at the University of Otago in memory of his son who was killed in World War I.[1][7][10] He also made donations to the University's medical library, a sports ground at Logan Park and a lamp of remembrance at Wellington College.[1] Barnett died on 28 October 1946.[4]
