The testosterone content was studied in 50 male patients, who sustained myocardial infarction, on the 1,3--5,10 and 20th day of the disease. Forty seven patients with ischemic heart disease served as controls. The results obtained were analysed in relation to the patients age and the course type of the disease. The testosterone concentration on the 1st day of myocardial infarction was not different from that in the ischemic heart disease patients. Elevation of the testosterone level was observed in the myocardial infarction patients during the acute period of the disease, but its dynamics depended on the course type of the disease. No relationship was revealed between the testosterone level increase and the patients age.