The present study was conducted to evaluate the hepatoprotective effect of puerariae Radix methanol extract on benzo(a) pyrene(B(a)P) - induced liver injuries in rats. In vitro experiment, primary cultured hepatocytes (5X105 cells/$mell$) were cultured for 20~24 hours after adding puerariae Radix mehtanol extract(32$mu extrm{g}$/$mell$) and B(a)P(50 uM). In vivo experiment, Puerariae Radix methanol extract(0.25 g/kg/day, per os) was administered for 7 days and B(a)P(0.1 mg/kg/day, intraperitoneally) was given after the last administration of extract. And then the hepatoprotective effect of Puerariae Radix methanol extract was investigated biochemically through in vitro and in vivo experiments. Namely, activities of enzymes (GOT, GPT and LDH) were measured and 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide(MTT) assay were carried out in vitro cell culture study and GOT, GPT, LDH and ALP activities and HDL-cholesterol, total cholesterol and triglyceride contents were performed in vivo study. In vitro experiment, as a result of enzyme activity measurement(GOT, GPT and LDH) and MTT assay, GOT,GPT and LDH activities changed by B(a)P were recovered to normal levels and hepatocytes impaired by B(a)P were recovered to normal. In vivo experiment, Puerariae Radix methanol extract significantly decreased the enzyme activities(GOT, GPT, ALP and LDH in serum and GPT and ALP in tissue) and lipid contents in comparison to B(a)P-treated group