Wanpae-tang is suggested to have antitumor activity on lung cancer. This study was performed to investigate antitumor, immune response, and apoptotic effects by Wanpae-tang in the cancer cell lines and C57BL/6 mice. Experimental studies were progressed through the anticancer activities such as, survival time, cell cytotoxicity, natural killer cell activity, productivity of interleukins and apoptotio effects. The results were summarized as follows: 1. Median survival time of Wanpae-tang treated group was prolonged to 4.1%, as compared with control group, but was not significant. 2. On the MTT assay, half-maximal inhibitory concentration(IC50) of Wanpae-tang was 15.00 ㎎/㎖ in HeLa cell, and 4.158 ㎎/㎖ in HRT-18 cell. 3. Natural killer cell activity in Wanpae-tang treated group was decreased in case of 100:1 and 10:1 effect cell/target cell ratio. 4. Production of interleukin-2, 4, 12 in Wanpae-tang treated group were significantly increased. 5. On the studies of Wanpae-tang induced apoptosis, a DNA fragmentation patterns were not appeared.