Abstract:A study has been made on the scavenging action of Shengmaiyin Decoction and its ingredients Radix Ginseng,Radix Ophiopogonis and Fructus Schisandrae on hydroxyl radical,as well as on the relationship between the decoction and its ingredients using ESR spin trapping.The results indicate that the decoction is better in antioxidation than its ingredients.