To investigate the effect of Sarcodon aspratus methanol extract on liver damage in benzo(a)pyrene (B(a)P)-treated mice, mice were divided into 4 groups of control, B(a)P, Sarcodon aspratus methanol extract and Sarcodon aspratus methanol extract-B(a)P. The activities of serum aminotransferase, cytochrome P-450 and hepatic content of lipid peroxide after B(a)P-treatment were increased than control, but those levels were significantly decreased by the treatment of Sarcodon aspratus methanol extract. On the other hand, the hepatic glutathione content and glutathione S-transferase activity were increased by the treatment of Sarcodon aspratus methanol extract. Also the activities of superoxide dismutase, catalase and glutathione peroxidase were decreased by the treatment of Sarcodon aspratus methanol extract. In addition cytochrome P-450 1A1 isozyme protein level, which was remarkably increased by B(a)P treatment from results of immuno blotting, was decreased by the treatment with methanol extract of Sarcodon aspratus. These results suggest that Sarcodon aspratus methanol extract have protective effect on liver damage by decreasing lipid peroxide and activities of free radical generating enzymes.