This study investigates the hepatoprotective activity of ethanol extract from Shidagonglao roots (SDGL(EtOH)). The hepatoprotective effect of SDGL(EtOH) (20, 100 and 500 mg/kg) was analyzed on carbon tetrachloride (CCl(4))-induced acute liver injury. Rats pretreated orally with SDGL(EtOH) (100 and 500 mg/kg) and silymarin (200 mg/kg) for 3 consecutive days prior to the administration of a single dose of 50% CCl(4) (0.10 ml/100 g of bw, ip) significantly prevented the increases in the activities of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in CCl(4)-treated rats. Histological analysis also showed that SDGL(EtOH) (100 and 500 mg/kg) and silymarin reduced the incidence of liver lesions including vacuole formation, neutrophil infiltration and necrosis of hepatocytes induced by CCl(4) in rats. Moreover, the SDGL(EtOH) (100 and 500 mg/kg) increased the activities of anti-oxidative enzymes, superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GRd) and decreased malondialdehyde (MDA) level in liver, as compared to those in the CCl(4)-treated group. Furthermore, SDGL(EtOH) (100 and 500 mg/kg) and silymarin attenuated the increased levels of tumor necrosis factor-alpha (TNF-alpha) in serum and nitric oxide (NO) in liver as compared to the CCl(4)-treated group. The hepatoprotective mechanisms of SDGL(EtOH) are likely related to inhibition of TNF-alpha, MDA and NO productions via increasing the activities of antioxidant enzymes (SOD, GPx and GRd). These experimental results suggest that SDGL(EtOH) can attenuate CCl(4)-induced acute liver injury in rats.