Aster scaber $T_{HUNB}$ (AST ; Charm-chui), a potent herbal medicinal plant, has a long tradition of use, being harvested as a wild plant, is said to stimulate appetite, and may act as a diuretic, antifebrile agent and painkiller. This study was conducted to investigate the immunomodulative effects of AST In mice, using in vitro and in vivo experiments. The immunomodulative effects were studied in vitro by measuring the proliferation of mice splenocytes and the production of three kinds of cytokines (IL-$eta$, IL-6, and TNF-$alpha$) by mice peritoneal macrophages which were cultured with sequential fractions of AST methanol extract (methanol, hexane, chlo-roform, ethylacetate, butanol and water). In an in vivo experiment using mice, different concentrations of AST water extract were orally administrated every other day for two weeks. The production of cytokines (IL-1$eta$, IL-6, and TNF-$alpha$) secreted by activated macrophages, and the proliferation of mice splenocytes, were used as indices for immunocompetence. In vitro supplementation using six fractions of AST in the range of 1 to 100$mu$ g/ml enhanced splenocyte proliferation by 10.5% to 53% compared to the control. IL-1$eta$production was significantly increased with the supplementation of butanol and water extracts of AST. Higher levels of IL-6 and TNF-$alpha$production were detected with supplementation of methanol, ethylacetate, butanol or water extracts at the concentration of 100$mu$ g/ml. In the in vivo study, the highest proliferation of splenocytes was seen in the mice orally administrated with the AST water extract at the concentration of 500mg/kg body weight. In the case of cytokine production, there were no significant differences in the production of IL-1$eta$and IL-6 among the treated groups and the control. However, TNF-$alpha$released by activated peritoneal macrophages were augmented by the oral administration of AST water extract. These results indicate that AST may enhance the immune functions by regulating splenocyte proliferation and cytokine production capacity in mice.