In this review, data have been assembled which demonstrates the profound and indisputably positive effect that North American (NA) ginseng (Panax Quinquefolium) has on the immune system in vivo in mice. The mouse was chosen because of the numerous parallels of this immune system to that of the human. Moreover, it has been shown that this immune-enhancing influence extends across all age groups from pre-weaning to old age and is gender independent. This consistently positive influence occurs in normal animals, which, moreover, maintain their elevated immune system even after discontinuing exposure to this agent. A distinct prophylaxis has been established thereby, such that ginseng-consuming animals, challenged with either tumor cells, or carcinogenic agents, have a level of resistance to the impending pathology not seen in parallel control animals. Moreover, it has been shown that in both leukemia-afflicted infant and adult mice, given this extract of NA ginseng, tumor abatement and significantly prolonged life span occurred. Thus, as an agent so effective in enhancing the mechanisms responsible for disease defense, its potential for debuting along side conventional, mainstream medicine, cannot be ignored.