The experiments were performed to investigate the effects of protein and protein hydrolysates on lipid metabolism in the hyperlipidemic/hypercholesterolemic rat model induced by feeding fat-enriched diet. In Except 1 male rats were fed four semi-purified high fat and cholesterol diets that contained different nitrogen source, casein(C), casein hydrolysate(CH), corn gluten(G) and corn gluten hydrolysate(GH), for 6 weeks. In Expt. 2 rats were fed high fat and cholesterol diet for 4 weeks to induce hyperlipidemia and hypercholesterolemia. Then the rats were divided into 4 groups and were fed the four kinds of above experimental diets for 4 weeks consecutively. The contents of total lipid , cholesterol and triglyceride in blood, liver and feces were determined. Serum lipid concentrations of CH, G and GH were significantly lower than that of C. Serum cholesterol concentrations of hydrolysate groups(CH and GH) were significantly lower than those of intact protein groups(C and G). Serum HDL -cholesterol concentration tended to increase by hydrolysate intake. The total lipid, cholesterol contents in liver showed similarity results as above. Fecal lipid excretions of CH, G, and GH groups were significantly higher than that of C group. These results indicate that hypolipidemic and /or hypocholesterolemic effect of corn gluten or protein hydrolysates were detected in the process of inducing hyperlipidemia by high-fat and cholesterol diet or after inducing hyperlipidemia.