In order to investigate the Immunomodulatory effects of ginseng, we have studied the effects of ginseng saponin on the proliferation and cytosine gene expression of human pheripheral blood mononuclear cell (PBMC). In the PBMC proliferation assay, total saponin exhibited proliferation inhibition on the PBMC or phytohemagglutinin(PHA)-stimulated PBMC in a dose-dependent fashion. Immunomodulatory effects of ginseng were further investigated using the cytokine gene expression as the indicators. In the reverse transcription-polymerase chain reaction (RT-PCR) test, interleukin (IL)-1, IL-2, IL-3, IL-4, IL-6, IL-13, granulocyte macrophage-colony stimulating factor, tumor necrosis factor (TNF), migration inhibitory factor and transforming growth factor genes were expressed in the PHA-stimulated PBMC 48 hrs after cell culture. Among expressed cytokines, total saponin could increase the expression of IL-1 and TNF of PBMC without stimulation of PHA. All of ginsenosides, $Rb_1$, $Rb_2$, $Rg_1$, Rc, Re, incresed TNF gene expression. Especially, Rb2 (20 g/ml) showed most prominent effect on TNF gene expression and it also slightly increased IL-1 gene expression of PBMC.