This research was designed to study the effect of Korean dietary lipids on the lipid metabolism and the immune function in young rats . The three different lipid sources were compared lard, perilla oil and fish oil. Three different levels of lipid in the diet, 2%, 15% and 30%,on the weight basis, were included. After four weeks feeding, the rats were sacrified and blood sample was collected to analyze for the total lipid, TG and cholesterol contents in serum. The HDL fraction in serum was seperated by the electrophoresis of lipoproteins. The immune responses were measured by the blastogenesis of spleen lymphocyte stimulated by PHA and in serum were measured. The following results were obtained. Lower body weight gain was shown in 30% lipid diet fed group on the isocaloric basis. In concerning the different dietary lipid sources, there were significantly lower boyd weight gain in fish oil than in perilla seed oil and lard group in 30% lipid groups. Deposition of body fat expressed by epididymal fat pad in serum were significantly different among perilla seed oil, lard and fish oil groups. Perilla seed oil group showed lowest level of total lipid and TG in serum regardless of dietary fat level. The feeding perilla seed oil to rats was resulted in lower serum cholesterol levels than lard in all three levels of fats tested. The HDL fraction was elevated in perilla seed oil group at the high fat level. The stimulating responses of lymphycotes by PHA did not seem to be influenced by different dietary fat sources. However, conA mitogenic responses was significantly increased in perilla seed oil group. The lower level of perilla seed oil (2%, 15%) showed slightly higher responses of ConA, indicating that lower level of perilla seed oil might have stimulatory response on the immune response. The number of antibody forming cells of spleen against SRBC was increased in 30% fat level for all the three kind of fats. However, no effect has been found in plaque forming cell response by the differences in dietary fat sources. There were no significant differences in serum IgG and IgA levels in all dietary groups.