Erytropoietin is a glycoprotein hormone produced by the kidney and it is the major humoral regulator of red cell production. It binds to specific molecules (EPOR - erytropoietin receptor) on the cell surface. The most sensitive to erythropoietin is the erythroid cell, specially between the CFU-E and the erythroblast. Recombinant human erythropoietin has been available for treatment of anemia of renal disease since 1989, later for other types of anemias. It is biologically equivalent to the natural erythropoietin. Therapy with this agent is safe and effective, and it substantially improves quality of live. The newer product of erytrhropoietin is called darbepoetin. It is highly related to erythropoietin, it binds to the same receptor, but it has a longer in vivo half-life than recombinant erythropoietin.