A retrospective study of autopsies was performed on patients who died of ischaemic heart disease (IHD) in the industrialised Ruhr valley of West Germany. Groups were classified on the basis of the presence or absence of cardiac scar tissue, acute myocardial infarction and cardiac rupture. Severe coronary atherosclerosis was not a constant finding in IHD, and ranged from 57% of acute coronary insufficiency cases in women to 86% of recurrent infarction cases in men. During the period 1970 to 1979 recurrent infarction decreased in frequency, whilst hearts with scar tissue in the absence of fresh infarction (chronic progressive coronary insufficiency) became increasingly common. These two groups accounted for 72% of IHD deaths and were more common in men than in women. However, the incidence of first-time acute myocardial infarction and acute coronary insufficiency was higher in women than in men. The frequency of clinically known diabetes mellitus and/or hypertension was higher in women with IHD than in controls. Systemic hypertension was not commoner in cardiac rupture cases than in other cases of acute myocardial infarction. Cardiac rupture increased markedly in the latter half of the last decade so that since 1974 20% of all acute myocardial infarcts showed cardiac rupture. The incidence of first-time infarction as well as anterior infarction was significantly higher in cases of cardiac rupture than in acute infarction without rupture. The incidence of recent coronary thrombosis was low in recurrent myocardial infarction (23%), higher in first-time infarction (39%) and highest in cardiac rupture (59%). In men, this finding was significantly higher in acute infarction with rupture than in acute infarction without rupture (p less than 0.001). The view of coronary thrombosis as a secondary phenomenon in acute myocardial infarction is supported.