Graduated from the University of New South Wales in 1998 and worked as a junior medical officer at St Vincent's Hospital, Sydney. He completed his cardiology training through the South Eastern Sydney Area Health Network and his PhD in Medicine through the University of Sydney. With the aim of specialising in electrophysiology, Rahn undertook 3 years of specialist training split equally between the Royal Prince Alfred Hospital in Sydney and Loyola University Medical Center in Chicago, USA.