Erwin Oechslin studied medicine in Zurich and then specialised in internal medicine and cardiology. This was followed by a two-year stay at the University of Toronto, where he focused on congenital defects in adults. After returning to the Clinic of Cardiology at the University Hospital of Zurich he was nominated Deputy Head of the Department and established, with immense commitment and competence, a consultation service for congenital defects. Simultaneously he worked at the echocardiography laboratory under Professor Rolf Jenni. In 2005 he was appointed Associate Professor of Cardiology and Director of the Program for Congenital Heart Defects in Adults by the University of Toronto, and was invited to work there.