The antioxidant effects of niacin (nicotinic acid) were investigated in doxorubicin (DXR)-induced chronic heart failure in rats. For the experiment 30 Wistar albino rats (180-220 g) were divided into three groups. The control group received normal saline for 5 weeks. Experimental chronic heart failure (CHF) was induced by administering DXR (5 mg/kg) intramuscularly once a week for 5 weeks; nicotinic acid was administered intraperitoneally daily (10 mg/kg) for 5 weeks. In this experiment we studied the changes in the concentration levels of superoxide anion radical (SOR), hydrogen peroxide (HP), lipid peroxidation (LPO) products (diene conjugates (DC), thiobarbituric acid active products (TBA-AP) and Schiff bases (SCHB), and changes in the superoxide dismutase (SOD) and catalase (CAT) activity in the myocardium of animals. The results indicate that niacin administration against the DXR background decreases the oxidant parameters (SOR, HR), increases the antioxidant parameters (SOD, CAT), and LPO reaches a normal level. The obtained results are indicative of free radical scavenging attenuation in cardiomyocytes in rats with chronic heart failure, which allows us to consider nicotinic acid as a product with cardioprotective activity.