Male rats of 2 months-old(young), 6 months-old(adult) and 30 months-old(old)were fed 8 or 16 weeks to investigate the e(feats of dietary fat level on the lipid metabolism in the different stages of aging. The response of 30 month old rats to dietary fat level differed from either 2 or 6-months old rats. In 30-months old rats, dietary fat level had a little effect on weight gains, lipid content of serum as compared with other two age groups. Young rats showed higher body weight gain, F.S.R, and PER compared with aged rat. The younger and the more high fat fed the rats were, the more body weight gains, FER and PER showed. Weight of liver and kidney was increased in aged rats but ratio per unit weight of liver and kidney was not affected by age. Serum lipid content was higher in aged rat compared with the young and liver lipid content was higher in high fat diet fed rats. But TG of liver and serum was not changed with aging process. Intake, excretion and absorption of lipid was not changed by age of animals. but absorption was decreased as experimental period was increased.