Désiré Collen was also Professor of Biochemistry and Medicine in the Department of Kenneth G. Mann at the University of Vermont College of Medicine, Burlington, Vermont, USA (1984–2005), Visiting Professor of Medicine in the group of Herman 'Chip' Gold of Massachusetts General Hospital at Harvard School of Medicine, Boston, MA, USA (1987–1994), Consultant in Medicine at the Massachusetts General Hospital, Boston, MA, USA (1987–2005) and Visiting Professor at the Division of Surgery and Anaesthesia of Kevin Burnand at United Medical and Dental Schools of Guy's and St Thomas' Hospitals, London, UK (1999–2002).