Anaemia commonly occurs in cancer patients receiving chemotherapy, often necessitating blood transfusion. This multicentre study was designed to evaluate the efficacy and safety of epoetin α in preventing the decline in haemoglobin (Hb) level, and to determine whether the transfusion requirement could be reduced, in patients receiving 4–6 cycles of primarily platinum-based combination cyclic chemotherapy for small cell lung cancer (SCLC). A total of 130 non-anaemic SCLC patients were randomized to receive no additional treatment (n = 44), epoetin α 150 IU kg⁻¹ subcutaneously (s.c.) three times a week (n = 42) or 300 IU kg⁻¹ s.c. three times a week (n = 44). Reductions in epoetin α dosage were made during the study if Hb level increased to >15 g dl⁻¹. The mean weekly dosage was 335 and 612 IU kg⁻¹, respectively, in the two active treatment groups. Significantly fewer (P < 0.05) epoetin α-treated patients experienced anaemia (Hb < 10 g dl⁻¹) during the course of chemotherapy (300 IU kg⁻¹, 39%; 150 IU kg⁻¹, 48%; untreated, 66%). This was reflected in the significantly lower number of treated patients transfused [300 IU kg⁻¹, 20% (P < 0.001); 150 IU kg⁻¹, 45% (P < 0.05); untreated, 59%]. Epoetin α was well-tolerated, and there was no evidence of sustained, clinically significant, hypertension. In summary, epoetin α is effective and well-tolerated in maintaining Hb level and reducing transfusion requirement in patients undergoing cyclic chemotherapy for SCLC. © 1999 Cancer Research Campaign