We investigated the immune enhancement effects of JaSaengHwan (JSH). The forced swimming test (FST) has been used as a screening model for new immune enhancement agents. We found that JSH (0.1 mg/ml) significantly reduced the immobility time in the FST compared to the control. Also, we investigated the effect of JSH on the proliferation of T cell and production of cytokines in human T-cell line, MOLT-4 cells and mouse peritoneal macrophages. JSH (1 mg/ml) significantly increased the cell proliferation by $46.78{pm}6.41%$ (p<0.05) and also significantly increased the interleukin (IL)-2, IL-4 and interferon $(IFN)-{gamma}$ production compared with media control (about 2-fold for IL-2, 3-fold for IL-4 and 1.5-fold for $IFN-{gamma}$, p<0.05) at 24 h. In addition, JSH increased the production of IL-12 on the mouse peritoneal macrophages (by 3.6-fold for IL-12, p<0.05). In conclusion, these data indicate that JSH may have an immune-enhancement effect.