The hypolipidemic mechanism of crocin, an active ingredient in Gardenia jasminoides Ellis and Crocus sativus L, was examined in rats. In diet-induced hyperlipidemic rats, a 10-day treatment with crocin significantly reduced serum triglyceride, total cholesterol, low density lipoprotein (LDL) cholesterol and very low density lipoprotein (VLDL) cholesterol level in the daily dose range of 25 to 100 mg/kg. Results of the modified fat-loading method indicated that crocin inhibited the absorption of fat and cholesterol and this inhibition is closely related to the hydrolysis of fat. In addition, the modified fat-balance method demonstrated that crocin increased the fecal excretion of fat and cholesterol in rats, but had no influence on the elimination of bile acids. The results of the in situ loop method and enzyme assay indicated that crocin could not directly block the absorption of cholesterol from rat jejunum but could selectively inhibit the activity of pancreatic lipase as a competitive inhibitor. These findings suggest that crocin yielded its hypolipidemic effect by inhibiting pancreatic lipase, leading to the malabsorption of fat and cholesterol.