This study assessed the influences of CVT-E002, a proprietary extract of North American ginseng, Panax quinquefolius (Afexa Life Sciences, Inc., Edmonton, AB, Canada), in vivo, on murine hemopoietic and immune cells when administered as a dietary additive. The extract was given daily to young, adult mice for a period of 4 weeks, immediately following which one group was euthanized and the hemopoietic and immune cells of their bone marrow, spleen and blood were assayed for CVT-E002-mediated alterations in any of five cell lineages (lymphocytes, nucleated erythroid cells, granulocytes, immature granuloid precursors and monocytes). Another group of these mice was left for a subsequent 8 weeks on control diet, following which the same organs and cell lineages were analysed. In another study, juvenile mice immediately upon weaning (age: 4 weeks), were subjected to the above protocol, and their organs/cell lineages assayed. The results revealed that CVT-E002 had a long-lasting, positive quantitative effect on the lymphocytes and monocytes, regardless of age at commencement of daily, dietary CVT-E002. CVT-E002 may therefore have a prophylactic disease defense, immunostimulatory role, or potentially, even a therapeutic role.