Objective : To investigate immune enhancing effects of Boummyunyuck-dan (BMD) Methods : In this study I investigated the effect of BMD on cell proliferation and viability. In addition, I investigated production of cytokines (IL-2, IL-4 and $IFN-{gamma}$), NO, and $TNF-{alpha}$ in human T-cell leukemia, MOLT-4 cells. The cells were cultured for 24h in the presence or absence of BMD. Result : BMD increased the cell viability by 15% (P<0.05) and enhanced IL-2, IL-4 and $IFN-{gamma}$ production compared with media control in a dose-dependent manner (P<0.01) at 24h. BMD also increased mRNA and protein expression levels of $IFN-{gamma}$ in MOLT-4 cells. In addition, I also assessed the effects of BMD on production of NO and $TNF-{alpha}$ from the peritoneal macrophages because NO and $TNF-{alpha}$ as a potent macrophage-derived immune reaction regulatory molecule has received increasing attention. However, BMD had no effect on NO and $TNF-{alpha}$ production in the cells. Conclusion : These data indicate that BMD has some immune-enhancing effect, and that its action may be due to the proliferation and cytokine production of T cells.