The purpose of this research was to investigate the effects of Kamidaebo-tang water extract (KDT) on murine peritoneal macrophages. KDT (50 or 250 mg/kg) was administerd p.o. once a day for 7 days to mice. KDT increased the production of tumor necrosis factor-α and nitric oxide from murine peritoneal macrophages, but decreased the production of interleukin-1β. Also, KDT enhanced the production of lucigenin chemiluminescence from peritoneal macrophages. These results suggest that KDT enhances the non-specific immune response via increase of tumor necrosis factor-α and nitric oxide and phagocytic activity from peritoneal macrophages.