Protective effect of scoparone against the acetaminophen inducible hepatic toxicity in mice was investigated. Scoparone (5mg/kg) was administered intraperitoneally to mice daily for 5 days. Scoparone pretreatment before the administration of acetaminophen has blocked subsequent increases in liver to body weight ratio. When biological changes were measured, scoparone protects against acetaminophen inducible hepatotoxicity in mice as evidenced by the decreased formation of lipid peroxide, lowered serum transaminase activity and the decreased level of serum acetaminophen. In conjuction with the results of Huh (Arch. Pharm. Res. 10, 165(1987)), these results suggest that the most likely mechanism for the observed protective effects of scoparone against the acetaminophen-induced hepatotoxicity is the induction of hepatic microsomal UDP-glucuronyltransferase activity.