Mechanism for whitening effect of flavonoid materials in Radix puerariae was studied via investigation of its inhibition action on tyrosinase and antioxidizing action. Laboratory test results showed that the inhibition effect of flavonoid materials in Radix puerariae on tyrosinase is stronger than that of arbutin and its concentration leading to 50% activity lost (IC50) was identified as 1..72 g ~ L i. The flavonoid materials in Radix puerariae displays a rather strong overall reducing action capacity and certain scavenging action capacity ag...