1956 -57 Sloan-Kettering Institute for Cancer Research New York; 1959-63 Children's Hospital University of Heidelberg; 1963-74 Children's Hospital University of Kiel; 1965 Forshungsstipendiat, Institut für Humangenetik Münster; 1968-69 Research Associate, Children's Hospital, Harvard University Boston; 1970-71 Visiting Professor, University of Madison Children's Hospital; seit 1974 Direktor, Children's Hospital, University of Mainz.