In spite of Echinacea-based products being among the best-selling herbs in the world to date, to allay assorted ailments, the debate is still on-going with respect to the efficacy of ingesting the herb intermittently, continuously, or only at the beginning of an affliction. We sought, therefore, to find out if mice, receiving dietary Echinacea daily, throughout life, from youth until late middle-age, demonstrated any longevity/survival differences, and/or any differences in their various populations of immune/ hemopoietic cells. Sustained and/or high levels of these cells are crucial for longevity. Some mice were maintained on a regular chow diet to which was added Echinacea purpurea daily (2 mg/mouse), from puberty (7 week) until just beyond 13 months of age (late middle-age in mice). Control mice, identically housed and maintained, received identical chow without the herb. Mice consuming untreated diet had a 79% survival by 10 months of age, while those consuming Echinacea daily in the diet were still 100% alive by 10 months. At approximately 13 months of age, mice consuming untreated diet had a 46% survival rate while those consuming Echinacea, were 74% alive at this time. Moreover, the key immune cells, acting as the first line of defense against developing neoplasms in mice and humans, i.e., natural killer (NK) cells, were significantly elevated in absolute number both in their bone marrow production site, as well as in the major organ to which they traffic and function, i.e., the spleen. The cells of the myeloid/granulocyte lineages remained steadfastly at control levels in both the bone marrow and spleen in Echinacea-consuming mice. Thus, it appears that regular intake of Echinacea may indeed be beneficial/prophylactic, if only for the reason that it maintains in an elevated state, NK cells, prime elements in immunosurveillance against spontaneous-developing tumors, a phenomenon which increases in frequency with progressive aging.