The effects of various dietary docosahexaenoix acid(DHA) levels on the brain phospholipids and serum and liver lipid compositions were studied in rats using DHA concentrated oil and corn oil as a control for 4 weeks. Serum total cholesterol and HDL cholesterol levels tended to be the lowest by adding 20% DHA to corn oil. Serum triglyceride levels significantly decreased by adding 30% DHA. Liver cholesterol and triglyceride levels were apparently decreased in the groups added above 20% DHA, especially, the lowest at adding 30% DHA. Brain weight and phospholipid content were not different among groups. The ratios of arachidonic to linoleic acids in serum and liver phosphatidylcholine(PC) were significantly decreased by adding dietary DHA and showed a flat form above 20% of dietary DHA. DHA levels of serum PC were gradually increased according to dietary DHA level. The fatty acid compositions of the brain PC and phosphatidylethanolamine(PE) did not appear any changes with accordance of the dietary DHA levels. However, compared with those of serum and liver in general, linoleic and arachidonic acid levels were very low. Oleic acids were apparently higher than those in the other tissues. DHA were higher than those in the other tissues rigardless of the dietary DHA, especially in brain PE. The ratios of arachidonic to linoleic acid were not apparent tendency in brain PC and PE. However, the ratios of brain PE were above 2 times higher than those of brain PC. As the results, the hypolipidemic effects of dietary DNA were remarkable in liver. Especially in regard to tendency of liver lipid levels and desaturation indices in serum and liver PC, the effects indicated significantly higher by adding 20-30% DHA to diet(n-6/n-3 ratio, about 4-7). Thus, in this study, these dietary DHA levels seemed to be appropriate, at least in these lipid paramenters.(Korean J Nutrition 34(2) : 132∼140, 2001)