The effect of the antioxidant histochrom on the size of the myocardial infarction and activity of the cardioselective enzyme creatine phosphokinase was studied in 45 patients with acute myocardial infarction during thrombolytic therapy. Changes in blood plasma histochrom concentration were studied in 7 patients with myocardial infarction after a single intravenous infusion of 100 mg of the drug. The pharmacokinetic parameters of the drug are shown. The use of histochrom in thrombolytic treatment of acute myocardial infarction lead to limitation of the necrotic zone and increase of myocardial contractility, and results in a more favorable course of the processes of left-ventricular remodeling.