Although the vegetable Angelica keiskei (AK) has widely been utilized for the purpose of general health improvement among Korean population, its functionalities are not very well defined. In this study, we examined the effects of methanol extract of AK in rats on the biochemical changes induced by two hepatotoxins, D-galactosamine (GalN) and carbon tetrachloride ( CCl₄). AK was orally administered once daily for 7 days to male rats at 200and 500 mg/kg, before hepatotoxins. Effects of AK were assessed 24 hr later. AK pretreatments at 200 and 500 mg/kg significantly blunted GalN-induced elevation in liver lipid peroxidation, plasma aspartate-transaminase (AST) and alanine-transaminase (ALT) activities. AK also prevented, after 500 mg/kg but not after 200 mg/kg, the GalN-induced elevation in triglyceride, total cholesterol and LDL-cholesterol levels. Differently from against GalN-induced toxicity,AK did further elevate the CCl₄-induced rise in AST, ALT and lipid peroxidation. These results suggest that AK, when pre-administered prior to GalN, exerted protective effects against GalN-induced hepatotoxicity, in contrast however,AK exacerbated that induced by CCl₄. To explore possible mechanism for the toxicity-potentiating effects of AK on CCl₄, the activity of hepatic drug metabolism after AK treatment was assessed. It was observed that AK increased the activity of aniline hydroxaylase, a cytochrome P450 isoenzyme responsible for metabolic activation of CCl₄. This finding suggests that hepatoprotective effects of AK are not equally expected depending on hepatotoxins employed.