Bidens pilosa L. var minor (Blume) Sherff, B. pilosa L. and B. chilensis DC (compositae), commonly known as "Ham-hong-chho" in Taiwan, have been traditionally used for medicinal purposes. To clarify and compare the hepatoprotective effects of these three plants, we evaluated their potential effectiveness on CCl4- and acetaminophen-induced acute hepatic lesions in rats. The results indicated that the increase in SGOT and SGPT activities caused by CCl4 (3.0 ml/kg, s.c.) and acetaminophen administration (600 mg/kg, i.p.) could be significantly reduced by treating with the extracts of all the three kinds of "Ham-hong-chho" and the extract of B. chilensis exhibited the greatest hepatoprotective effects. These phenomena were also confirmed by histological observation. Liver damage induced by CCl4 and acetaminophen was markedly improved in the extract of B. chilensis treated groups, while groups treated with the extracts of B. pilosa var minor and B. pilosa demonstrated only moderate protective effects. The pharmacological and pathological effects of these three crude groups were compared with Bupleurum chinense, which has been reported previously as a treatment criteria in the CCl4 model, and with silymarin as a standard reference medicine in the acetaminophen model. The results suggest that B. pilosa var minor, B. pilosa and B. chilensis can protect liver injuries from various hepatotoxins and have potential as broad spectrum antihepatic agents.