One hundred and ten cases of heart rupture (27%) were found among 408 postmortems of acute myocardial infarction from 1976 to 1982. After intensive care units were introduced the rate of rupture increased from 17% to 30% and reached 39% of the total. Ruptures were more frequent in women (32%) than in men (24%), their frequency increasing with the age; average age was 70 years in men and 72 years in women. Sudden death occurred in 16% of the patients; the interval between the first symptoms of infarction and death was 24 hours in 39% and 1 week or less in 90% of those affected. Most cases with extremely short history showed a fully developed infarction at autopsy. The rupture was, in fact, the first manifestation of latent ("silent") infarction. Less usual types of heart rupture (incomplete rupture, i. e. dissection of the free wall of the left ventricle and rupture of interventricular septum or papillary muscles of the left ventricle) are discussed in detail. Practical experience of the study is summarized in comments on heart autopsy.