Herba Xanthii(HX), Radix Xantluii(RX) and Fructus Xanthii(FX) is one of the oriental medicine that has been used for the treatment of such infectious diseases and tumors. However, the mechanism of the drug is not investigated much. This study was done to know the effects of HX, RX and FX extract on the such innate immunities as phagocytic function and reactive radical formtions from phagocytes and the such acquired immunities as humoral and cell-mediated immunities. The followings are the results obtained from this study: 1. HX2 and FX1 groups increases the in vivo phagocytic activity of mononuclear phagocytes. 2. HXB, RXB, RXC, FXB and FXC groups increase the in vitro phagocytic activities. 3. RXB group stimulated the macrophages to produce nitric oxide in the presence of $interferon-{gamma}$ $(IFN-{gamma})$. 4. HX and RX whole groups increased the luminol-amplified reactive oxygen intermediate production in vivo. 5. HX whole and RX1, FX2 groups increased the lucigenin-amplified reactive oxygen intennediate production in vivo. 6. HXC group only increased the luminol-amplified reactive oxygen intermediate production in vitro. 7. HXB, FXB and FXC groups increased the lucigenin-amplified reactive oxygen intermediate production in vitro. 8. HX2, RX1 and FX whole groups increased the hemolysin formations from B cells. 9. HX, RX and FX whole groups significantly increased the rosette forming cells from the spleen. 10. HX, RX and FX whole groups significantly decreased the delayed-type hypersensitivity measured by footpad swelling. The above results demonstrate that HX, RX and FX has enhancing effects on innate immunity selectively and decreasing effects on delayed-type hypersensitivity of cell-mediated immunity according to medicinal part and diluted condition. This immunomodulating effects of HX, RX and FX might be responsible for the treatment of immune-mediated disorders.