Prof. Guy John Maddern was raised in Adelaide, South Australia, and completed medical school and surgical training at the University of Adelaide. After gaining Fellowship in the Royal Australasian College of Surgeons (RACS), he headed overseas to Bern, Switzerland, to work with Prof. Leslie Blumgart, MB, ChB, MD, for two years and then another year in Rennes, France, with Professor Bernard Launois, MD, FACS(Hon).
Shortly after returning to Adelaide in 1993, he was appointed the R.P. Jepson Professor of Surgery at the University of Adelaide at the age of 36. He assumed the role of head of upper gastrointestinal and hepatobiliary surgery and head of the division of surgery, The Queen Elizabeth Hospital. In 1997, the RACS created the Australian Safety and Efficacy Register of New Interventional Procedures–Surgical (ASERNIP-S) and appointed him as director. The ASERNIP-S has now become a world authority on the assessment of new surgical technologies, with a longstanding relationship with the American College of Surgeons.
Subsequently, he served as chair of the International Network of Agencies for Health Technology Assessment (2006–2009). He also has been president of the Health Technology Assessment International (2015–2017) and was a councilor of the RACS (2003–2011). In 1996, he became the director of the Basil Hetzel Translational Research Institute based at The Queen Elizabeth Hospital.
With a reorganization of hospital services in South Australia, the Royal Adelaide Hospital amalgamated with The Queen Elizabeth Hospital, and Professor Maddern became director of surgery of both institutions in 2013, a role he held until August 2019. During this time, the old Royal Adelaide Hospital moved to a new site in Green Fields, South Australia, in what has been the most challenging of moves in recent times. In recent years, his ongoing focus has been directed to publishing, a higher degree of supervision, and research funding totaling more than $70 million.