The antioxidative activities of water-soluble extracts from leaves and stem bark of Morus alba and Cudrania tricuspidata were compared in vitro experimental models. Antioxidative activities were measured by inhibition activity against lipid peroxidation of mouse liver microsome, and they were showed in the following order; stem bark of C. tricuspidata(53%)$gt;stem bark of M. alba(43%)$gt;leaves of C. tricuspidata(38%)$gt;leaves of M. alba(43%). In antioxidative activities determined by thiocyanate method and TBA method, the water-soluble extract of stem bark of C. tricuspidata showed the highest antioxidative activity. The water-soluble extracts of leaves were slightly stronger than other extracts in DPPH(α,α`-diphenyl-β-picrylhydrazyl) method. The concentrations of total polyphenolic compound from water-soluble extracts of leaves and stem bark of M. alba and C. tricuspidata were 1.32%, 1.28%, 1.34% and 1.30% respectively. In these results, the water-soluble extract of stem bark from Cudrania tricuspidata showed the highest antioxidative activity.