Aim: To study the effects of osthole on hyperlipidemic fatty liver and investigate the possible mechanisms. Methods: A rat model with hyperlipidemic fatty liver was successfully established by feeding fatty milk for 6 weeks. The experimental rats were then treated with 5-20 mg/kg osthole for 6 weeks. The mouse hypedipi-demic model was induced by feeding fatty milk when they were treated with 10-20 mg/kg osthole for 3 weeks. Results: After treatment with osthole, the levels of rat serum total cholesterol (TC), triglyceride (TG) and low density lipoprotein-choles-terol significantly decreased as compared with the fatty liver model group (P＜0.05 or P＜0.01). Hepatic weight and its coefficient, the hepatic tissue contents of TC,TG, and malondialdehyde, also significantly decreased (P＜0.05 or P＜0.01). In fatty milk-induced hyperlipidemic mice, the post-heparin plasma activities of lipo-protein lipase (LPL), hepatic lipase (HL), and total lipase (TL) significantly increased after treatment with 10-20 mg/kg osthole for 3 weeks (P＜0.05 or P＜0.01).Importantly, the histological evaluation of rat liver demonstrated that osthole dramatically decreased lipid accumulation (P＜0.01). Conclusion: Osthole was found to have therapeutic effects on fatty milk-induced rat fatty liver; the mecha-nisms might be associated with its anti-oxidation and the elevation of the activi-ties of LPL and HL.