Gamisipjundaebo-tang (GSDBT) has been used for the purpose of development of physical strength. In the present study, we investigated the immune enhancing effect induced by GSDBT. We investigated the anti-immobility effect of GSDBT via a forced-swimming test and blood biochemical parameters related to fatigue, glucose, blood urea nitrogen, lactic dehydrogenase, creatine kinase, and total protein. GSDBT (0.1 and 1 g/kg) was orally administered to mice for 14 days. After 7 and 14 days, as assessed through a forced-swimming test, immobility time was decreased in the GSDBT-administrated group (0.1 and 1 g/kg) in comparison with the control group. In addition, after 8 days, the contents of glucose and lactate dehydrogenase in the blood serum were increased, and contents of blood urea nitrogen were decreased in the GSDBT-administrated group. After 15 days, the contents of glucose were increased, and the contents of lactate dehydrogenase and blood urea nitrogen were decreased in the GSDBT-administrated group. However, it had no effect on the elevation of creatine kinase and total protein level. We also investigated the effect of GSDBT on the production of cytokines in human T-cell line, MOLT-4 cells, and splenocytes. GSDBT significantly increased interferon (IFN)-gamma and interleukin (IL)-2 levels compared with the media control but did not affect IL-4. GSDBT increased the protein expression of IFN-gamma in MOLT-4 cells. These results suggest that GSDBT may be useful in immune function improvement and may also have antifatigue properties.