Untreated anemia is common in cancer patients. Previous studies have demonstrated that both the existence of cancer and treatment with chemotherapy can suppress the normal endogenous erythropoietic response to anemia, making some cancer patients transfusion cadidates. In placebo-controlled phase III studies, administration of recombinant human erythropoietin (epoetin alfa) increased hemoglobin (Hb) levels and decreased transfusion requirements in patients undergoing cancer chemotherapy. In these studies, an increase in self-perceived energy level, functional status, and overall quality of life (QOL) was noted in the subset of patients in whom hematocrit levels increased by > or = 6%. To examine more closely the relationship between epoetin alfa therapy and QOL issues in patients undergoing chemotherapy, we conducted an open-label phase IV study involving 2,030 patients treated at 570 community cancer centers in the United States. Patients initially received epoetin alfa 150 U/kg subcutaneously (s.c.) three times per week for 4 months; if response was judged inadequate, the dosage was increased after 8 weeks to 300 U/kg s.c. three times per week. Hb levels and transfusion requirements were monitored monthly. Before and after the study, each patient completed a linear analog self-assessment scale designed to measure energy level, daily activity, and overall QOL. During epoetin alfa therapy, there was a progressive and significant increase (P < .001) in Hb concentrations. Significantly fewer (P < .001) patients were transfused and fewer transfusions were administered per patient per month after the first month of epoetin alfa therapy. Fifty-eight percent of the patients who required a transfusion during the first month of epoetin alfa therapy did not require a transfusion during the subsequent 3 months of the study. The entire patient population demonstrated a significant increase in mean scores for energy level, daily activity, and overall QOL. The magnitude of the increase in these scores correlated with the magnitude of the increase in Hb concentration. Statistically significant improvement in energy scores, daily activity, and overall QOL (P < .05) were observed, regardless of tumor response. These observations require confirmation on placebo-controlled trials, but the implications for oncology practice are important. They suggest that in cancer patients undergoing chemotherapy, the tradition of leaving anemia untreated may compromise patients' ability to function and their QOL.