Cardiac and plasma activities of marker lysosomal enzymes were studied in Wistar rats with metabolic (epinephrine) and occlusion (ligation of coronary arteries) myocardial infarction. Activity of all examined lysosomal enzymes significantly increased in the myocardium and blood plasma starting from the first day after ligation of the coronary arteries and was accompanied by leukocytic infiltration of the myocardium. Enzyme activity gradually decreased to postoperation day 14. In metabolic infarction leukocytic infiltration and specific activity of lysosomal enzymes rose gradually and attained maximum to postoperation day 14, while the signs of labilization of lysosomal membranes appeared from the first postoperation day. Plasma activity of lysosomal enzymes in metabolic infarction increased smoothly and peaked on day 14.