Dried seeds of Camellia japonica and Thea sinensis were investigated to determine the nature of their antioxidative activity. Activity was measured by the induction period in the coupled oxidation of a substrate lard and extracts or isolates to be tested. 70% methanol and dichloromethane extracts were found to be antioxidative abilities. Their unsaponifiables revealed weak antioxidative activity, although hexane extracts did not show antioxidative effect on lard. Column chromatography for dlchloromethane extracts gave 4 fractions(only 2 fractions were potent). HPLC was used in isolating potent antioxidative components from the column fractions and the precolumn-passed methanol extracts. They were separated into 7 and 8 components, respectively. The column fractions obtained from both seeds comprised trans-p-coumaric acid. trans-p-ferulic acid and an unknown component with minor components such as chlorogenic acid and catechin. On the other hand, the most prominent components in the methanol extracts were an unidentified component. trans-pcoumaric acid, trans-p-ferulic acid, catechin and chlorogenic acid. The unknown compound isolated from the column fractions and methanol extracts was identified as epicatechin by $^1H-and;^{13}C-NMR$. The antioxidative activities of these components were epicatechin > catechin > chlorogenic acid > trans-p-ferulic acid > trans-p-coumaric acid.