Sheng-mei-san (SMS), a traditional Chinese formulation comprising Radix Ginseng, Radix Ophiopogonis and Fructus Schisandrae, has long been used for more than 700 years for patients with coronary heart disease. We attempted to clarify 1) whether SMS reduces myocardial infarct size, and 2) whether the infarct size-reducing effect of SMS is related to activation of protein kinase C and the opening of the mitochondrial KATP channels in Japanese white rabbits without collateral circulation. The results indicate that three days treatment but not acute treatment with SMS reduces myocardial infarct size through activation of protein kinase C and opening of the mitochondrial KATP channels.