This study investigated the hypolipidemic and antithrombotic effects of linolenic acid derived from Korean perilla oil. The experimental rats(male, Sprague-Dawley) were divided into 5 groups using a Randomized Complete Block Design and fed one of the five following diets : DO*/O#. D4/O, D4/4, D4/8, or D4/20(D*/# represents the ratio of linoleic to linoenic acid as the percentage of total dietary energy intake) for 4 or 8 months. Bleeding time and whole blood clotting time were determined and the composition of serum and platelet lipids analyzed. Comparisons from the DO/O to the D4/20 group showed that serum lipids (total lipid, triglyceride, total cholesterol, and HDL-cholesterol) gradually decreased with increasing linolenic acid intake - the hypolipidemic effect. The composition of platelet fatty acids[the ratio of eicosapentaenoic acid(EPA)/arachidonci aci(AA)] increased gradually with increasing linolenic acid intake. Higher linolenic acid intake increased bleeding time and whole blood clotting time, and decreased malondialdehyde(MDA) production in the platelets, though no significant differences. These results suggest that linolenic acid derived from perilla oil appears to suppress the conversion of linoleic acid to AA and the EPA transformed from linolenic acid appears to suppress the conversion of AA to TXA2. Since TXA2 is a platelet-aggregating and vasoconstricting agent, the redulction of TXA2 released by platelets with increasing intake of perilla oil containing a lot of linolenic acid confers an antithrombotic effect.