Summary. Darbepoetin alfa is a novel erythropoiesis-stimulating protein with a prolonged serum half-life. This randomized, double-blind, placebo-controlled, dose-finding study investigated the efficacy and safety of darbepoetin alfa in anaemic patients with lymphoproliferative malignancies who were receiving chemotherapy. Patients were randomized in a 1:2:2:1 ratio to receive darbepoetin alfa 1·0 μg/kg (n = 11), 2·25 μg/kg (n = 22), 4·5 μg/kg (n = 22) or placebo (n = 11), administered subcutaneously once weekly for 12 weeks. No dose increases were allowed during the study. A higher proportion of patients achieved a haemoglobin response (defined as a ≥ 2·0 g/dl increase from baseline) in the darbepoetin alfa 1·0 μg/kg (45%), 2·25 μg/kg (55%) and 4·5 μg/kg (62%) groups than in the placebo group (10%; P < 0·01). The mean change in haemoglobin from baseline to week 13 was 1·56 g/dl in the 1·0 μg/kg group, 1·64 g/dl in the 2·25 μg/kg group and 2·46 g/dl in the 4·5 μg/kg group, compared with a mean change of 1·00 g/dl in the placebo group. The overall safety profile of darbepoetin alfa in this study was similar to that of placebo. These results show that darbepoetin alfa effectively and safely increased haemoglobin concentrations in patients with lymphoproliferative malignancies. Confirmative studies at doses of 2·25 and/or 4·5 μg/kg/week in this population are warranted.