The purpose of this paper is to describe the differences in mineral, ascorbic acid, and total polyphenol content, and also the relationship between polyphenol content and antioxidant activity(DPPH radical scavenging, FTC, and TBA methods) in three sizes of Cudrania tricuspidata leaves. For the mineral contents of the leaves, Ca was highest(17.26 mg/g.d.w.), followed by K(15.53 mg), P(2.61 mg), and Mg(1.99 mg). Ascorbic acid was found to be slightly higher(43.4 mg/100g.f.w.) in the basal parts of the medium size leaves and lowest in the whole parts(9.9 mg) of the small size leaves. Total polyphenol content was highest($1,384{sim}1,258mg/100g.f.w.$) in the leaves, for all sizes, when extracted with 80% ethanol, followed by the stem bark(543 mg%), roots(369 mg%), stems(243 mg%), and thorns(223 g%). By determining DPPH activity, we found that antioxidant activity was higher in the ethanol extracts of the leaves than in the ethanol extracts of the thorns, stems, roots, and stem bark. While in the tea, no differences were found between the ethanol and water extracts.