Panax ginseng has been used for various diseases including hepatic disorders. The aim of the present study was to investigate the hepatoprotective effects of ethanol extract and saponin of Panax ginseng in thioacetamide-intoxicated rats and to compare with silymarin, a known hepatoprotective agent. Male Sprague-Dawley rats were given single intragastric administration of thioacetamide. Aqueous solutions of ethanol extract and saponin of Panax ginseng with or without silymarin were administered intragastrically daily for six days from four days before until one day after thioacetamide administration. At the end of the treatment, the rats were fasted overnight and sacrificed. As a result, thioacetamide caused significant increase in serum levels of AST, ALT, 5'-nucleotidase and bilirubin. Thioacetamide increased Ca++ content but decreased protein content in liver tissue. These thioacetamide-induced biochemical changes were prevented both by ethanol extract of ginseng and silymarin, but not by ginseng saponin. Silymarin did not potentlate the effect of either ethanol extract or saponin of ginseng on these parameters. Thioacetamide-induced confluent necrosis was not protected by the test drugs. In conclusion, ethanol extract of ginseng protects the liver possibly by stabilizing the cell membrane and by inhibiting thioacetamide-induced Ca++ increase in the hepatocytes, which was comparable to that of silymarin.