To investigate the effects mustard leaf(Brassica Juncea) on Cholesterol metabolism, male Sprague Dawley rate were fed semipurified diets containing 2% or 4% mustard leaf with or without cholesterol for 5 weeks. Plasma cholesterol content decreased significantly by feeding 4% mustard leaf with of without cholesterol for 5 weeks. Plasma cholesterol content decreased significantly by feeding 4% mustard leaf in rats fed 1% cholesterol in the diet. In addition, HDL-cholesterol increased slightly by the feeding of mustard leaf, resulting in a significant increase in the HDL-cholesterol/total cholesterol ratio and a reduction of atherosclerotic index. However, levels of plasma lipids were not influenced by mustared leaf in rats fed cholesterol-free diet. The contents of all classes of lipid in liver increased by dietary cholesterol. Of the liver lipids, triglyceride and cholesterol ester were accumulated most, showing a fatty liver synodrome. Supplementation of mustard leaf to cholesterol-containing diet resulted in a slight decrease in neutral lipid contents of liver. Fecal cholesterol excretion was higher by more than 2.7 and 3.3-fold in rats fed 2 and 4% mustard leaf than in control rats fed cholesterol. Similar trends were found in fecal bile salt excretion; rats fed and 4% mustard leaf excreted more bile salts by more than 1.5 and 2% than those fed control diet containing cholesterol. In summary, mustard leaf may have an antiatherogenci effect of reducing plasma cholesterol level and increasing HDL-cholesterol level. The plasma cholesterol lowering effect of mustard leaf is suggested to be due, at least in part, to increase in fecal excretion of cholesterol and bile acids.