The incidence of risk factors for atherosclerosis was investigated in a group of 846 patients under 65 years of age, hospitalized with acute myocardial infarction (AIM) in coronary hospital units in 21 districts of the Czech Republic in 1996. The group of patients comprises 649 men and 197 women. The incidence of risk factors in patients was compared with the incidence of risk factors in the population of the Czech Republic: the mean values of the investigated indicators are in patients with AIM higher in both sexes (total serum cholesterol, triacylglycerols, BMI, WHR). As to anamnestic data, in the majority low or irregular physical activity predominates, a high percentage of patients reported that they "do not restrict" or "rather do not restrict" their total food intake nor the intake of animal fats. Among the patients 52.6% males and 42.1% females were smokers. The results indicate that patients with AIM have a higher incidence of risk factors for atherosclerosis, a higher percentage of patients have cumulated risks and a higher percentage of patients has a higher risk score than the general population. The incidence of AIM is markedly higher in subjects with lower education.