In 650 consecutive patients with first acute myocardial infarction the time interval between the first anginal attack and the acute infarction as well as the time interval between onset of symptoms suggestive for acute myocardial infarction and hospitalization were evaluated. Our results demonstrate that in 25% of patients the history of angina was less than 24 hours, in 50% of all patients less than three days; furthermore, the time interval from onset of symptoms of acute myocardial infarction to hospitalization correlated with the history of angina; the depression of left ventricular function after myocardial infarction was independent of a previous history of angina; in patients with a very short history of angina there was a significantly higher incidence of single vessel disease. Thus, prevention of acute myocardial infarction would have been possible only in about half of the patients with impending myocardial infarction due to the short duration of preceding angina.