To investigate the effects of ginsenosides from Panax ginseng on mitogenic responses in macrophages and splenocytes from murine, we examined the effects of representative protopanaxadiol and protopanaxatriol ginsenosides ($Rb_1,;Rb_2,;Re;and;Rg_1$) on tumor necrosis factor-${alpha}$ (TNF-(${alpha}$) production in murine macrophage cell line (RAW264.7 cells) stimulated by lipopolysaccharide (LPS) and T cell proliferation in splenocytes stimulated by concanavalin A (Con A). Among the ginsenosides tested, protopanaxadiol ginsenosides ($Rb_1;and;Rb_2$) significantly inhibited TNF-${alpha}$ production in a dose-dependent manner. However, protoppanaxatriol ginsenosides (Re and $Rg_1$) showed little inhibitory activity. The molar concentrations of $Rb_1;and;Rb_2$ producing 50% inhibition ($IC_{50}$) of TNF-${alpha}$ production were $55.8{mu}g/ml;(48.0{mu}M);and;31.8{mu}g/ml (27.9{mu}M)$, respectively. As a positive control, prednisolone also exhibited inhibitory activity with an $IC_{50}$ value of $21.7{mu}M$. In T cell proliferation, $Rg_1$, was not effective but $Rb_1$ and Re or $Rb_2$ significantly increased or inhibited at high concentration, 75 and $100{mu}g/ml$. In contrast, prednisolone showed potent inhibitory activity with an $IC_{50}$ value of 6.1nM. These results suggest that ginsenosides may take part in the mitogen-induced signaling pathway for TNF-${alpha}$ production and T cell proliferation from macrophages and splenocytes.