Patients with HIV infection frequently develop clinically significant anemia, either as a manifestation of the HIV or as a result of therapy with medications such as zidovudine. Therapy with recombinant human erythropoietin can increase hemoglobin levels in these patients, decreasing transfusion requirements and improving some aspects of the quality of life. Once erythropoietin therapy is started, it is important to monitor patients carefully for the development of iron deficiency and erythrocytosis.