Mung bean, adzuki bean, black bean and rice bean are foods and folk medicines of Taiwan. We evaluated the effects of various water extract concentrations (100, 500 and 1000 mg/kg body wt.) and silymarin (25 mg/kg body wt. on acetaminophen-induced liver injury by measuring serum glutamate-oxalate-transaminase (sGOT) and serum glutamate-pyruvate-transaminase (sGPT) activities in rats. The results showed that the sGOT and the sGPT activities, increased by APAP, were decreased significantly (P < 0.05) through treatment with inceasing amounts up to 1000 mg/kg body wt. of the exracts. In particular, the mung bean aqueous extract showed the best hepatoprotective effect on APAP-induced hepatotoxicity. The pathological changes of liver injury caused by APAP improved by the treatment with all of the legume extracts, which were compared to silymarin as a standardized drug. In addition to these results, the extract of mung bean acted as a potential hepatoprotective agent in dietary supply.