Effects of heating conditions and seed roasting on the lipid oxidation and antioxidants of perilla seeds were studied. Perilla seeds, that were unroasted or roasted at $180^{circ}C$ for 20 min, were ground and heated over steam at $100^{circ}C/1$ atm or at $135^{circ}C/2$ atm. Lipid oxidation was evaluated by peroxide value, conjugated dienoic acids contents, and fatty acid composition. Tocopherols and polyphenols were also determined. Lipid oxidation of perilla seeds was higher during heating at $135^{circ}C/2$ atm than at $100^{circ}C/1$ atm, and the oxidation rate was lower in unroasted seeds than in roasted seeds. Degradation of tocopherols and polyphenols in perilla seeds during heating was faster under high pressure and temperature, and was decreased by seed roasting. Contribution of polyphenols to the oxidative stability of perilla seeds during heating was higher than that of tocopherols, suggesting polyphenols and seed roasting as important factors in lipid oxidation of perilla seeds.