Experimental studies obtained in recent years indicate the urgency of developing drugs of complex action to prevent the development of cardiovascular disease in dogs. This requires a much deeper study of the pathogenesis of heart failure, including cardiomyopathy. The aim of the study was the effect of bendamine on the intensity of lipid peroxidation and the activity of the antioxidant defense system of blood in rats in experimental doxorubicin-induced cardiomyopathy. To reproduce heart failure in rats, an experimental model was used by intraperitoneal administration of doxorubicin at a dose of 2.5 mg/kg 3 times a week for two weeks. The study was performed on white sexually mature young male Wistar rats weighing 180–200 g, which were kept on the standard diet of the institute vivarium of the State Research Control Institute of Veterinary Drugs and Feed Additives. For the study, three groups of rats of 6 animals in each were formed: control group – intact animals; experimental group R1, in which animals were simulated doxorubicin-induced cardiomyopathy by intraperitoneal administration of doxorubicin; experimental group R2, in which animals after injection of doxorubicin, intragastrically administered the drug “Bendamine” at a dose of 20 mg/kg. According to studies, doxorubicin intoxication in rats enhances LPO processes, as indicated by an increased content of lipid hydroperoxides by 47.4 %, diene conjugates – by 21.4 % and TBA-active products – by 24.9 % for animals of the control group. Doxorubicin cardiomyopathy in rats has a decrease in the activity of antioxidant enzymes in the blood of animals. In particular, the activity of catalase decreases by 36.9 % (P ≤ 0.001), and the activity of SOD – by 20.3 % (P ≤ 0.001). In the study of the activity of the glutathione link of the antioxidant defense system, similar changes were found as in the study of the activity of catalase and SOD. The use of the drug “Bendamine” in the rats of the experimental group helped to inhibit the excessive formation of lipid peroxidation products and increase the activity of both enzymatic and non-enzymatic parts of the antioxidant system.