The treatment of anemia in patients with renal failure has been dramatically changed with the development of recombinant human erythropoietin (r-HuEPO). This review discusses the pathogenesis of the anemia renal failure and the biology of erythropoietin. Causes of poor response to r-HuEPO therapy are outlined, and the importance of adequate available iron is highlighted. Parameters used to measure iron adequacy include serum iron levels, transferrin saturation, and ferritin levels. Other nutritional deficiencies, such as folic acid and vitamin B-12, can also impair r-HuEPO response. Clearly, the advent of r-HuEPO treatment for patients with renal failure and anemia has brought another dimension to the care of these patients. Optimal nutrition management is critical for the success of this new agent.