Abstract: AIMTo study the mechanism of action of ginsenoside Rg₁ and its metabolite Rh₁ on the function of immunocyte in normal mice. METHODSThe proliferation of splenocytes was determined by using MTT assay. Phagocytosis activity of peritoneal macrophages was determined by using neutral red phagocytosis assay. Griess agent was used to assay the NO-releasing level of peritoneal macrophages. RESULTSRh₁ was shown to promote proliferation of splenocytes directly, down-regulate the Con A-induced proliferation of T-lymphocytes. Rg₁ can not induce proliferation of splenocytes directly, while Rg₁ 100 μg·mL^-1 can inhibit ConA-induced proliferation of T-lymphocytes obviously. Both Rh₁ and Rg₁ showed no effect on LPS-induced proliferation of B-lymphocytes. Rg₁ and Rh₁ were found to significantly increase the phagocytosis and NO-releasing level of peritoneal macrophages, while the effect of Rh₁ is weaker than that of Rg₁. CONCLUSIONThe immuno-regulation effect of Rg₁ may be carried out by both Rg₁ and its metabolite Rh₁. Their functions on other immunocytes still need further study.