Darbepoetin alfa is an erythropoiesis-stimulating agent (ESA) approved for treating chemotherapy-induced anemia. This phase II, double-blind, placebo-controlled study examined the efficacy of darbepoetin alfa for treating anemia of cancer (AoC) in patients not receiving chemotherapy or radiotherapy. Patients were randomized 3:1 to receive darbepoetin alfa (6.75 microg/kg) or placebo every 4 weeks; the end of the study was at week 17. The primary endpoint was the percentage of patients with a hematopoietic response. Secondary endpoints included transfusion incidence and safety parameters. Efficacy analyses were performed on 162 patients in the darbepoetin alfa group and 56 patients in the placebo group. The Kaplan-Meier percentages of patients who achieved a hematopoietic response (darbepoetin alfa, 69%; placebo, 24%) or achieved the target hemoglobin (darbepoetin alfa, 85%; placebo, 50%) differed significantly between treatment groups. The transfusion incidence did not differ between treatment groups probably because of the low baseline transfusion rates in AoC patients. The incidence of adverse events (including on-study deaths) was similar in both groups. In conclusion, darbepoetin alfa appeared to be well tolerated and significantly increased hemoglobin levels in these AoC study patients.