Agaricus blazei Murill (ABM) is enriched with polysaccharides, lipids, vitamins, fibers and minerals. Many studies have shown that ABM possesses immune-enhancing and anti-tumor effects. However, little is known about its protective effects on liver function. We employed carbon tetrachloride (CCl(4)) to induce hepatic fibrosis in a rat model to examine the protective effects of ABM on the liver in this study. The experiments included non-treatment control, CCl(4)-only control, and treatment with 200 mg and 2,000 mg of ABM extracts (per kilogram rat weight). All groups other than the non-treatment control were treated with intraperitoneal injections of CCl(4) twice a week. Experimental and control rats were tube-fed with experimental ABM extracts or double-distilled water, respectively, on the remaining four days each week. The whole experimental protocol lasted 8 weeks; blood and liver samples were collected for biochemical and tissue histochemical analysis. Plasma alanine aminotransferase and aspartate aminotransferase, and the activities of the anti-oxidative enzymes glutathione peroxidase, superoxide dismutase and catalase in the liver were measured. We found that high-dose ABM treatment reduced hepatic necrosis and fibrosis caused by CCl(4) in comparison with the CCl(4) control group. ALT and AST activities in the sera collected from ABM-treated rats were lower than those in the CCl(4) control rats. These results suggested that ABM extract was capable of either enhancing liver recovering from CCl(4) damage or attenuating CCl(4) toxicity. Results of anti-oxidative enzyme activity analysis showed no apparent differences among ABM-treated groups and CCl(4) control groups, indicating that removal of free radicals does not explain the protective/recovery effects observed in this study.