Antioxidant properties of yantocine, a preparation derived from Alhagi pseudalhagi Desy, were studied on a model of acute toxic hepatitis induced in random bred young male albino rats (90-100 g). Two experimental models were used: acute geliotrine hepatitis and acute CCl4 hepatitis. Yantocine was added to preparations of damaged plasma membranes (PM) in ascending doses. The results indicate that the level of malonic dialdehyde in the rat liver PM depended on the drug dose in both models of hepatitis. Linear dependence was observed for doses of 1.0-5.0 gamma. The capacity of yantocine to decrease the production of lipid peroxided was confirmed in vivo. After 3-day treatment with yantocine the level of lipid peroxides decreased by 15 and 12%, respectively, while the content of total phospholipids increased negligibly.