This study was carried out to evaluate antioxidative, cytotoxic and chemosensitizing effects for anti-tumor activities of Naesosungma-tang (NST). The results were as follows ; 1. The oxidative effects were measured by DPPH radical scavenging activity. NST water extract was showed more effective than ethanol extract and also various solvent fractions from NST showed effective in the following order : butanol fraction > ethyl acetate fraction > hexane fraction > aqueous fraction. 2. NST water extract was showed cytotoxic effects on the human cancer cells Calu-6 cell and SNU-601 cell, but not on MCF-7 cell. 3. The viability of cells was measured in 4 kinds of solvent fractions from water extract of NST by MTT assay. The results were as followings : 1) On the NIH3T3 cell, $IC_{50}$ value was $200{sim}300;{mu}g/m{ell}$ in three fractions except aqueous fraction. 2) On the Caco-2 cell, effective only in the butanol fraction. 3) On the Calu-6 cell, most effective in hexane fraction($IC_{50}:80;{mu}g/m{ell}$) and effective in ethyl acetate and butanol fraction($IC_{50}:100{sim}120;{mu}g/m{ell}$). 4) On the MCF-7 cell, $IC_{50}$ value was similar in three fractions except aqueous fraction. 5) On the SNU-601 cell, $IC_{50}$ value was within $100;{mu}g/m{ell}$ in three fractions except aqueous fraction. 6) On the HCT-1l6 cell, $IC_{50}$ value was $150{sim}200;{mu}g/m{ell}$ in three fractions except aqueous fraction. 7) On the AML-2/WT cell, not effective in four kinds of solvent fractions. 4. In combined effects of NST and vincristine on AML-2/D100 cell, water and ethanol extracts of NST and hexane fraction of water extracts of NST more effectively inhibited proliferation of AML-2/D100 cell. These results Suggest that NST has antioxidative and cytotoxic effects against Caco-2, Calu-6, MCF-7, SNU-601, HCT116 and NIH3T3 cell especially Calu-6 and SNU-601 cell, and also chemosensitizing effects against AML-2/D100 cell in combined vincristine.