In this study, we investigated the hepatoprotective effects of four compounds from Galla Rhois [gallic acid methyl ester, gallic acid, an equilibrium mixture of 3-galloyl-gallic acid and 4-galloyl-gallic acid isomers, and 1,2,3,4,6-penta- O-galloyl- beta- D-glucose (PGG)] in primary rat hepatocytes undergoing necrosis or apoptosis. Treatment with gallic acid methyl ester (12.5 and 50 microM) or PGG (3.125, 12.5 and 50 microM) reduced hepatocyte necrosis induced by tert-butyl hydroperoxide. PGG treatment (4 and 20 microM) also altered hepatocyte apoptosis induced by glycochenodeoxycholic acid. Based on these results, we propose that PGG warrants further evaluation as a hepatoprotective agent, because it protected primary rat hepatocytes from both necrosis and apoptosis.