Acanthopanax divaricatus var. albeofructus (ADA) have been shown to have various levels of activity such as antioxidant, anticancer, antivirus, and immunostimulatory effects. However, little is known about its mechanism related to the modulation of immune activities. In this study, a water extract of ADA leaves were used to treat human peripheral blood mononuclear cells (hPBMC) to determine the underlying mechanisms for the immunostimulatory effects. To characterize its immunomodulatory activity, the secretion level of various cytokines including IL-2, IL-4, IL-6, IL-10, IL-12, IFN-$gamma$, and TNF-$alpha$ were measured using enzyme-linked immunosorbent assay (ELISA). Treatment of hPBMC with ADA leaf extract in an in vitro experiment induced various Th1 cytokines in a dose-dependent manner. A significant increase of IL-2, IL-12, IFN-$gamma$, and TNF-$alpha$ secretion was observed in the presence of ADA leaf extract. In contrast, Th2 cytokines including IL-4 and IL-6 were suppressed. There was no significant change in IL-10 release. Our results showed an increase in Th1 and a decrease in Th2 cytokine secretion which suggests that ADA may influence the immune response towards a predominance of Th1 cytokines in the immune system.