Brown practised medicine for a time at the Royal Canberra Hospital. During his tenure at the hospital, he and other senior medical staff took a pacifist stance by refusing to certify young men who did not wish to fight in the Vietnam War as fit to be conscripted.[4] He then worked as a resident at Darwin and Alice Springs hospitals. At the latter post, he met John Hawkins, a surgeon who had kayaked rivers in Tasmania.[4]