In 1984, 640 coronary events were registered in six districts of the Czech Socialist Republic in a population of 164, 185 men aged 25 to 64 years; in a population of 166, 651 women of the same age-group there occurred 162 coronary events. 695 coronary events were according to criteria of the MONICA project (Monitoring of Cardiovascular Diseases and their Risk Factors) confirmed as definite or possible myocardial infarction (MI). The incidence of MI per 100,000 inhabitants amounted in 1984 to 347.7 in men and to 74.4 in women aged 25 to 64 years. The death-rate up to the 28th day of the disease is in men and women the same: one third of patients with a coronary event die within 4 weeks after the onset of symptoms. Death occurs in 75.8% of men and in 69.2% of women during the first 24 hours. Of all subjects with fatal MI, 35.4% of men and 56.1% of women died in hospital.