In 1967 cardiologists in Switzerland were struck by the sudden increase in the number of cases of so-called primary pulmonary hypertensive disease (PPHD). Up untill966, the cardiology centers in Switzerland had not seen more than one or two cases a year, but this number suddenly multiplied by ten or twenty times. At the June 1968 meeting ofthe Swiss Society of Cardiology, Gurtner et al. (1968b) presented a paper which raised the question whether the vascular types of cor pulmonale had increased. They also raised the question about the possible responsibility of environmental factors, such as toxins or drugs, in causing this increase. Krrihenbuhl et al. (1968) first suggested the possible responsibility of anorexigenic drugs, but no proof was provided. Soon after this, the cardiology team in Bem (Gurtner et al., 1968a) published their report, which resumed and completed the above-mentioned prelim- inary communication; 31 cases of PPHD, among which 17 had taken an anorexigenic drug, aminorex fumarate (Menocil, Cilag), were reported. The importance of this work was soon recognized and it was followed by several meetings (in Vienna, Hannover, and Burgenstock) and two round tables sponsored by the Swiss Society of Cardiology (in Montreux and Basel).