The antioxidant action of Artemisia camprestris was examined in vitro and in vivo. A water extract of A. campestris showed a strong scavenging action of 1, 1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl and superoxide anion radicals. When the extract was given intraperitoneally to mice prior to carbon tetrachloride (CCl 4) treatment, CCl 4-induced liver toxicity, as seen by an elevation of serum aspartate aminotransferase and alanine aminotransferase activities, was significantly reduced. Depression of the elevation of serum enzyme levels after CCl 4-treatment was also observed by oral administration of the extract. In that case, CCl 4-derived lipid peroxidation in the liver was decreased by the extrac treatment. These results suggest that the extract of A. comprestris scavenges radicals formed by CCl 4 treatment resulting in protection against CCl 4-induced liver toxicity.