This study was performed to investigate effect of dried powder or ethanol extracts of onion flesh and peel intakes on lipid metabolism, antioxidative and antithrombogenic capacities in l6-month -old rats. Total of 40 Sprague-Dawley male rats of l6-month-old and weighing 816$pm$6g were blocked into 5 groups according to body weight and raised for three months with control and experimental diets containing 5% (w/w) of dried powders of onion flesh or peel or ethanol extracts from equal amount of each dried powder. Contents of total flavonoids and total dietary fibers in peel powder were highest among onion preparations. Body weight gain and epididymal pad fat weight were lower in peel powder group than other groups. Plasma total lipid, triglyceride and total cholesterol concentrations of onion-containing groups were lower than control group. Above all, peel ethanol extract intake decreased them most remarkably. Plasma HDL-cholesterol concentrations in onion-containing groups were higher than control group, especially that of flesh powder group was the highest among groups. Liver total lipid, triglyceride and total cholesterol concentrations were not significantly different among all experimental groups. However, liver total lipid and triglyceride concentrations were tended to be lower in onion-containing groups than control group. Thiobarbituric acid reactive substances (TBARS) concentrations in LDL + VLDL fraction was not significantly affected by onion intakes, However peel powder group showed the lowest concentration, Plasma TX $B_2$ concentrations in onion flesh powder, peel powder and peel ethanol extract groups were lower than control group, while plasma 6-keto-PG $F_{1a}$ concentrations in these same groups were higher than control group. Clotting time was tended to be increased in peel ethanol extract group. In conclusion onion diets seemed to improve lipid metabolism and antithrombogenic capacity while effect on antioxidative was not significant.t.