As mammals age, the cells of the immune system (IS) decline quantitatively and functionally, concomitant with which diseases such as cancer progressively increase in frequency. We have previously demonstrated in normal, juvenile mice that a specific, proprietary extract of North American ginseng, i.e., CVT-E002, is capable of significantly, quantitatively stimulating IS cells. We have previously revealed that the mechanisms responsible for the low numbers of immune cells seen in both juvenile and aging mice are very different. In the present study, we assessed the ability of CVT-E002 to restore/stimulate the declining immune cell numbers of aged mice. CVT-E002 (80mg in 6 gm chow/mouse) was added to the chow daily of 22 month old (= approximately 70 human years) normal, female C3H/HeN mice for 5 weeks. At 5 wk, the spleen and bone marrow were analyzed quantitatively for their content of lymphocytes, NK cells (the first line of defense against developing neoplasms), and “other” cells, i.e., those of the various hemopoietic lineages. Since the bone marrow is the central generating site of all NK cells, the observed significant augmentation in the numbers of these cells in that organ after consuming CVT-E002 for only 5 wk, necessarily reflects a CVT-E002-mediated stimulation of the production of new cells in this important tumor defense mechanism.