Macrophages play an important role in the first line of immunologic effects against tumor cells. The effects of nonsaponin red ginseng (NSRG) components on macrophage functions like tumoricidal activity, phagocytic activity, and NO production in young (8-weeks-old) and aged (82-weeks-old) male C57BL/6 mice were assessed in vitro, respectively. The treatment of tumor cells (melanoma B16 cells) with the supernatants of NSRG-treated macrophages resulted in an increase of cytotoxicity at 300 $mu$g/ml in the aged mice, whereas the supernatants did not have a cytotoxic effect in the young mice. It was observed that the supernatants induced the increase of tumor cell proliferation at 150 $mu$g/ml in the young mice, suggesting that the supernatants contain growth factors rather than cytotoxic molecules. In addition, NSRG alone had a direct cytotoxic effect on the B16 tumor cells. NSRG had no effect on the NO production by the macrophages in the young mice, while it significantly increased the level of NO release in the aged mice. There was no difference in the phagocytic activities of the macrophages by NSRG in both groups of mice. These results suggest that NSRG has differential effects on the macrophage functions in young and aged mice.