Erythropoiesis-stimulating agents (ESA) improve the hemoglobin level of roughly half the patients receiving chemotherapy for solid tumors or for blood diseases. These figures vary highly between studies. On average, 6 of these patients must be treated with ESA to prevent a transfusion for one patient. The impact of ESA prescription on quality of life is difficult to assess in the studies available today. The medicoeconomic analyses are on the whole unfavorable to the prescription of ESA for chemotherapy-induced anemia. This analysis might change if there were a way to select the patients highly likely to respond to ESA. Concern also exists about the potential negative impact of ESA prescription on patient survival when the objective of the prescription is to normalize hemoglobin. International guidelines must be followed to ensure that under treatment hemoglobin is always less than 12 g/dL.