Anaemia is a common complication in the treatment of patients with aggressive non-Hodgkin lymphoma (NHL), but there are no published data on the effect of erythropoiesis-stimulating agents in such patients. This is the first open-label, phase II, dose-finding study to evaluate the efficacy and safety of continuous erythropoietin receptor activator (C.E.R.A.). Ninety-three anaemic patients with aggressive NHL who were receiving chemotherapy (including many advanced NHL, heavily pretreated patients) were randomised to receive 2.1, 4.2 or 6.3 microg/kg C.E.R.A. subcutaneously once every 3 weeks for 12 weeks. Haematopoietic response was achieved in 45%, 57% and 65% of patients at the respective dose level. During weeks 5-13, the mean haemoglobin changes from baseline in the intent-to-treat population were increases of 0.2, 2.4, and 5.7 g/l in the 2.1, 4.2, and 6.3 microg/kg treatment groups, respectively, and 4.4, 5.7 and 6.8 g/l in the per-protocol population at the respective dose levels. C.E.R.A. was generally well tolerated in all three groups. C.E.R.A. appeared to have dose-dependent clinical activity in most anaemic patients with aggressive NHL who were receiving chemotherapy.