Isatis indigotica is commonly used as traditional chinese medicine for antipyretic, antiviral, and detoxifying purpose in China. In order to examine whether it prevents lipid peroxidation, root of Isatis indigotica was extracted with methanol and fractionated with hexane, ethyl acetate, butanol and water. The activity was evaluated by DPPH method and lipid peroxidation in rat liver homogenate and C $u^{++}$ -induced oxidated LDL. The results showed that ethyl acetate fraction and indigo, which is known as its constituent, had significantly anti-lipid peroxidative effects.s.