This Phase II study evaluated the combination of two active agents in small cell lung carcinoma (SCLC): carboplatin and ifosfamide. Thirty previously untreated patients (27 men and 3 women) with a median age of 59 years were included in this study. Twelve patients had one metastatic site and 18 had two or more metastatic sites. The median performance status was 80%. The chemotherapy (CT) regimen administered during the course of this study consisted of carboplatin (300 mg/m2) and ifosfamide (4 g/m2) plus mesna every 4 weeks. All 30 patients were evaluable: 1 achieved a complete remission (CR) and 18 achieved a partial remission (PR) (objective response rate, 63%). The median response time was 3 months and the median survival time was 8 months (range, 1 to 25+ months). Bone marrow toxicity was Grade III in three patients and Grade IV in four patients. The carboplatin and ifosfamide combination was well tolerated. No cross-resistance with the doxorubicin and etoposide regimen was established because 4 of 11 patients responded to this combination (+/- cisplatin) after failing to respond to the ifosfamide and carboplatin regimen. The ifosfamide and carboplatin combination may be considered for inclusion in non-cross-resistant alternating CT schedules.