Purpose: To prospectively evaluate the effectiveness safety, and clinical benefits of once-weekly epoetin alfa therapy as an adjunct to chemotherapy in anemic cancer patients. Patients and Methods: A total of 3,012 patients with nonmyeloid malignancies who received chemotherapy were enrolled onto this multicenter, open-label, nonrandomized study conducted in 600 United States community-based practices. Patients received epoetin alfa 40,000 U once weekly, which could be increased to 60,000 U once weekly after 4 weeks dependent on hemoglobin response. Treatment was continued for a maximum of 16 weeks. Results: Among the 2,964 patients assessable for efficacy, epoetin alfa therapy resulted in significant increases in hemoglobin levels, decreases in transfusion requirements, and improvements in functional status and fatigue as assessed by the linear analog scale assessment (energy level, ability to perform daily activities, and overall quality of life) and the anemia subscale of the Functional Assessment of Cancer Therapy-Anemia questionnaire. Improvements in quality-of-life parameters correlated significantly (P < .001) with increased hemoglobin levels. The direct relationship between hemoglobin and quality-of-life improvement was sustained during the 16-week study period, which is similar to findings of large community-based trials of three-times-weekly dosing. Once-weekly epoetin alfa was well tolerated, with most adverse events attributed to the underlying disease or concomitant chemotherapy. Conclusion: The results from this large, prospective, community-based trial suggest that once-weekly epoetin alfa therapy increases hemoglobin levels, decreases transfusion requirements, and improves quality of life in patients with cancer and anemia who undergo concomitant chemotherapy. Based on the results of this study, the clinical benefits and the adverse event profile of once-weekly epoetin alfa therapy in community-based practice are similar to those observed in the historical experience with the three-times-weekly dosage schedule.