AbstractRecombinant human erythropoietin (rHuEPO) is an agent commonly used by athletes with the aim to improve performance in endurance sports. However, the scientific community continues to debate the risks, benefits and its mechanism of action when used as a doping agent. This paper provides a brief overview on the pros and cons of rHuEPO use, as discussed by a group of scientist with diverse background, at the 17th Conference of the European Society for Clinical Hemorheology and Microcirculation in Pecs, Hungary. Among multiple topics, panel members challenged the common belief that the increased circulating hemoglobin concentration is the simple key to the improved sporting performance. Rather, hemorheologists developed the concept of optimal hematocrit (Hct), a Hct value that represents the optimal balance between the oxygen transport capacity of blood and blood viscosity. While guideline-directed transfusion therapy is advantageous under pathological conditions, such as severe anemia related to chronic kidney disease, its beneficial effects on endurance in healthy athletes remains questionable. Further studies are warranted in the field evaluating the effects of rHuEPO that are independent of increasing hemoglobin concentration, such as peripheral vasodilation and tissue metabolic changes.