Objective: To study the effects of andrographolide on immune functions and the immune mechanism in clinical therapy.Methods: The amounts of IFN-α,IFN-γ, TNF-α, IL-8 in the peripheral blood mononuclear cells (PBMC) culture supernatants dealt with by different concentrations of LianBiZhi (LBZ) injection, the effective component of which is andrographolide, were detected by biological activity test or ELISA in vitro. The effects of LBZ injection on macrophage phagocytotic function and natural killer cells cytotoxicity were examined by means of macrophage to phagocytize cock erythrocyte and measurement of lactate dehydrogenase (LDH) activity released from the damaged cells, respectively.Results: The LBZ injection could not only enhance the phagocytosis activity of peritoneal macrophage from guinea pig to phagocytosis cock erythrocytes, but also augment the cytotoxicity mediated by natural killer cells from PBMCs.Conclusion: Andrographolide is an immunostimulant agent which can modulate both antigen specific and nonspecific immune function by means of its natural killer cells, macrophage and cytokines.