||Sheng Mai San (SMS), a traditional Chinese formulation comprising Radix Ginseng, Fructus Schisandrae and Radix Ophiopogonis, is used for the treatment of coronary heart disease. The role of the lignans (lignan-enriched Fructus Schisandrae extract and Schisandrin B) in the cardioprotective effect of SMS was examined. Cardioprotective effects of chronic (7 g/kg/day x 30 day) and acute (17 g/kg/day x 3 day) lignan-enriched SMS (LgESMS) pretreatment in rats were observed in isoproterenol (in vivo) and ischemia-reperfusion (ex vivo) bioassay models. It is postulated that LgESMS plays a dual role in protecting the myocardium. LgESMS may provide a modulating effect in the β1-receptor mediated activity(ies) and at the same time it neutralizes the oxidative effects of free radicals. Schisandrin B present in the lignan-enriched Fructus Schisandrae extract, an constituent of LgESMS, may be responsible for the antioxidative action observed in LgESMS. Pretreatment of rats with Schisandri.n B at increasing oral daily doses of 0.3 - 0.9 mmol/kg for 3 days showed a dose-dependent protection against ischemia-reperfnsion injury. Further studies on the mechanisms of protection by Schisandrin B have provided evidences that Schisandrin B exerts its antioxidant effect by enhancing the endogenous glutathione and ascorbic acid content as well as glutathione peroxidase activity in the cardiomyocytes. These results showed obvious benefits of the lignans in the cardioprotective action of SMS. By enhancing the lignan content in SMS, we can have a fortified formulation of SMS which may improve the therapy and provide preventive measure of coronary heart disease.