We conducted a phase II study of ifosfamide and etoposide chemotherapy in patients with untreated extensive-disease small-cell lung cancer to assess response and toxicity. Between January 1994 and December 1995, 16 patients were treated. Ifosfamide and etoposide doses were ifosfamide 2 g/m2, with mesna, i.v. infusion over 30 minutes on days 1-3 and etoposide 80 mg/m2 i.v. over 120 minutes on days 1-3 every 4 weeks for up to six cycles. All patients were evaluable for toxicity profile and treatment response. As expected, the major toxicity was myelosuppression. With one exception, grade 3 or 4 leukopenia occurred in all patients during treatment, and 48.7% of the total courses had grade 3 or 4 leukopenia. Nine of 16 patients (56.3%) experienced episodes of febrile neutropenia. One toxic death due to febrile neutropenia with sepsis was documented. Toxicities other than leukopenia were few and mild in severity. After two cycles of treatment, the overall response rate was 81.3% (95% confidence interval 62.2-100) in this study. The median duration of response was 8 months and median survival was 11 months. In conclusion, ifosfamide and etoposide is an active combination regimen with acceptable toxicity profile in Chinese patients with extensive-disease small-cell lung cancer.