Intravenous glialin in a dose of 7 mg/kg suppressed the number of ectopic contractions caused by double ligature of the left coronary artery by the method of Harris and almost 2-fold prolonged animal life-span in comparison with the control. The maximum antiarrhythmic effect of glialin developed after 180 min and persisted for 5 h. Glialin injected intravenously (10 mg/kg) after myocardial infarction under conditions of programmed electrical stimulation inhibited conduction of evoked impulse in the atria, Purkinje fibers, and ventricular myocardium and did not modify the effective refractory periods of the atria and ventricles.