The water extract from the root of Salvia miltiorhiza Bunge showed a protective effect on cultured rat hepatocytes against carbon tetrachloride (CCl4)-induced necrosis. A further study was carried out to isolate the active constituent. Activity guided fractionation of the extract and chemical analysis gave us lithospermate B (a salt of lithospermic acid B), a tetramer of caffeic acid. Lithospermate B was also found to have a potent hepatoprotective activity in not only in vitro but also in vivo experimental liver injuries induced by CCl4 or D-galactosamine (D-GalN)/lipopolysaccharide (LPS).