We investigated the effect of fresh Rehmanniae radix methanol extracts (RGMeOH) on the in vitro production of cytokines by splenocytes and peritoneal macrophages isolated from C57BL/6 mice. Peritoneal macrophages and splenocytes were incubated with various concentrations of RGMeOH in the presence of $10;{mu}g/ml$ of lipopolysaccharide (LPS) $1;{mu}g/ml$ of concanavalin A (Con A) for cytokine assay, These results showed that RGMeOH remarkably attenuated LPS-increased production of $TNF-{alpha}$ but not IL-6 by peritoneal macrophages and enhanced LPS-stimulated production of IL-10 in a dose-dependent manner RGMeOH significantly augmented the LPS- or Con A-stimulated production of IL-2 and $IFN-{gamma}$ by splenocytes. These findings suggest that RGMeOH may attenuate inflammatory responses through down-regulation of $TNF-{alpha}$ and up-regulation of IL-10, and that RGMeOH may up-regulate cell-mediated immune responses through increase in IL-2 and $IFN-{gamma}$ production.