It is well established that an increase in circulating EPO can result in an increase in oxygen transport capacity and that an increase in oxygen transport capacity may result in an increase in the ability to perform endurance exercise. Echinacea has been used therapeutically in both oral and injected forms and is purported to enhance immune status through an increase in the activity of and/or the circulating concentration of components of the immune system.There is evidence that suggests Echinacea may stimulate the production of EPO and influence erythropoiesis through two separate mechanisms: 1) the activation of macrophages and subsequent production and release of PGE2 and 2) by increasing the activity level of T cells and subsequent production and release of erythroid progenitor growth factors. An increase in the circulating concentration of PGE2 is postulated to result in and increase in EPO production directly and indirectly through stimulation of CD4 and CD8 production from T cells. Evidence also exists to support the role of direct stimulation of T cells by Echinacea that may result in production and release of GM-CSF and IL-3. Thus, if Echinacea supplementation were shown to stimulate EPO production then an increase in [RBC] and oxygen transport capacity might also result. Finally, an increase in oxygen transport capacity with Echinacea supplementation may provide a therapeutic means by which to diminish the adverse effects caused by a decrease in oxygen availability and enhance endurance exercise performance through the same mechanism.