Erythropoietin (EPO) is a glycoprotein produced primarily by the kidney in response to tissue hypoxia, and is the principal factor regulating red blood cell production. It stimulates erythroid precursors in the bone marrow to proliferate and mature into morphologically identifiable red blood cells. This hormone acts by binding to specific high-affinity receptor on erythroid precursors. Failure to produce adequate quantities of EPO leads to severe anemia, a situation most often encountered in patients with end stage renal disease. With the application of recombinant DNA technology, the gene for this hormone has been molecularly cloned, sequenced and expressed in a biologically active form in mammalian cells. The recombinant EPO has been demonstrated to correct anemia in patients with severe end stage renal disease and alleviate their transfusion requirements. It has also been studied for anemia associated with HIV infection/zidovudine therapy, in cancer, rheumatoid arthritis, and prematurity. In addition it has been studied as a facilitator of autologous blood predeposit in patients scheduled for elective surgery and as a perisurgical adjuvant to hasten hematologic recovery and possibly avoid the need for homologous transfusion after elective surgery. When administered with the current guidelines EPO appears to be safe drug with favorable risk/benefit ratio.