SUMMARY Erythropoietin (EPO) is a glycoprotein hormone which is essential for normal erythrocyte production in bone marrow in healthy subjects. It induces erythropoiesis under hypoxic conditions. It is released from renal peritubular cells and various extrarenal tissues like liver, spleen, brain, lungs, bone marrow, reproductive organs. Interaction of EPO with its receptor (EPO-R) decreases programmed death (apoptosis) of erythroid progenitor cells and promotes their differentiation in bone marrow. Clinically, rHuEPO (recombinant human EPO) has been used since the late 1980s in patients with anaemia due to EPO deficiency as a consequence of chronic renal failure. In addition to erythroid progenitor cells, a varied group of cells including neurons, endothelial cells, vascular smooth muscle cells, and cardiac myocytes express EPO-R. It has been shown that Epo has cytoprotective properties against ischemia reperfusion damage and hypoxia in the brain, heart, kidneys, retina, liver, lungs, and intestines. It was suggested EPO. In addition to inhibition of apoptosis, EPO exhibits many other actions that serve to protect cells either directly or indirectly. EPO should therefore be regarded also as a general tissueprotective cytokine.