The protective activity of rosmarinic acid (RosA) on bromobenzene induced oxidative liver damage and antioxidative capability in mice was examined.Mice were treated with bromobenzene,after they were pre-given i.g.with rosmarinic acid and ascorbic acid (VC) respectively.The content of malonaldehyde (MDA) and the activity of antioxidative enzyme system in the liver were assayed.Results suggest that rosmarinic acid had stronger antioxidant ability of keeping the activity of antioxidative enzyme system in organisms and inhibiting Lipid peroxidation to protective the effects of bromobenzene-induced oxidant damage in mice than ascorbic acid by intragastrical administration 100~ 150mg/kg body weight everyday.