Ginseng contains various health-beneficial bioactive compounds, such as ginsenosides and polysaccharides. Despite ginseng marc is produced after the extraction process and usually discarded as wastes, it still contains considerable amounts of potential bioactive compounds, including saponins and polysaccharides. Previously, we reported that glucan type ginseng oligosaccharides obtained by enzyme hydrolysis of ginseng marc-derived polysaccharides exhibit immunostimulatory activities in macrophages and, activated macrophages are in turn capable of inhibiting the growth of skin melanoma cells via induction of apoptosis. In the present study, an enzymatic hydrolysate (GEH) containing these ginseng oligosaccharides was prepared and immune-enhancing activities of GEH were evaluated in vivo using cyclophosphamide-treated immune-suppressed mice. Immunosuppression was induced by 3 day-intraperitoneal (i.p.) injection of cyclophosphamide in mice. When comparedh normal control group, the GEH administered orally for 29 days facilitated the recovery of weight gain, indices of spleen and thymus, and enhanced T lymphocyte and B lymphocyte proliferation, cytokine productions of IL-6, IL-4 and IL-10 in culture supernatants of Con A-treated splenic T lymphocytes, and increased the serum levels of IL-4 and IL-10 as well as NK cell activity. These results demonstrated that administration of GEH stimulates and enhances immune function in immune-suppressed mice. The results of this study suggest that GEH of ginseng marc can be developed as a health-beneficial food material with immunostimulatory activity.