To observe the effect of dietary n6 linoleic acid, n6 gamma-linolenic acid and n3 alphalinolenic acid aon plasma lipid composition and platelet aggregation, twenty college women were divided into 4 groups and treated for 2 weeks with experimental diets supplying fat at 23% cal which were different only in fatty acid composition. Dietary fat was corn oil(CO) as a source of n6 linoleic acid(LA), perilla oil(PO) for n3 alpha-linolenic acid(ALA) and evenign primrose oil(EPO) for n6 gamma-linolenic acid(GLA). Plasma cholesterol level was slightly decreased by PL(13.5g) but significantly increased by equal amount of CO. However, there was similar hypocholeaterolemic effect when double amount of CO(27.0g), was supplemented. Therefore, total fat unsaturation may be more important factor for plasma cholesterol-lowering effect than the structure of fatty acid itself. Plasma cholesterol level was not lowered by supplement of GLA in CO diet. There was similar trend in hypotriglyceridemic effect by PO and CO as in plasma cholesterol. Plasma TG level was rather increased but not significantly by GLA supplement to CO diet. Overall, plasma lipid-lowering effect was greater by ALA than LA and GLA effect was not greater than by LA. GLA supplement did not significantly improve lipid compositions to prevent against CHD. There was no significant change both in fatty acid composition in platelet and ADP-induced platelet aggregation by GLA supplement to corn oil diet and by ALA in PO diet in young women.