In a retrospective study by means of a half-standardized method of interview in 154 patients with acute myocardial infarction and in a control group of the same age (n = 100) anamnestic data were established, particularly taking into consideration the preinfarction phase. 27% of the patients were surprised by an acute myocardial infarction without prodromal symptoms, in 32% the first occurrence of complaints of angina pectoris was during the last two months before the infarction. 41% had a preexisting angina pectoris which usually showed a crescendo-course with increasing approximation to the infarction. More than half of the patients reported on physical activity or/and emotional stress as causal factors of the preinfarction complaints. The correlation with the localisation of the infarction showed above all an occurrence of the prodromal symptoms in infarctions of the anterior wall and in lesions of the myocardium which in most cases could be ascertained only enzymatically. A greater accumulation of the prodromi was furthermore found in younger patients, in hypertension and preexisting restriction of the heart function. 70% of the patients with warning symptoms consulted a physician because of their heart complaints. In the control group 22% of the persons reported on heart complaints.