The aim of this phase II trial was to evaluate the efficacy and safety of a combination chemotherapy containing irinotecan (CPT-11) and carboplatin as first-line treatment of patients with small cell lung cancer (SCLC). From December 2002 to May 2004 61 patients with limited disease (IASLC classification) were enrolled who were not suitable for concurrent chemo-radiotherapy. Eighteen of the 61 patients (29.5%) had malignant pleural or pericardial effusion and 4 patients (6.6%) had involved supra- or infraclavicular lymph nodes. Patients received irinotecan 50mg/m(2) on days 1, 8 and 15 and carboplatin AUC 5 on day 1, every 4 weeks. A total of 233 chemotherapy cycles were administered. The median number of cycles per patient was 4. The overall response rate to chemotherapy on an intention-to-treat basis was 64%. The median overall survival was 13.8 months, the median disease-free survival 8.0 months, the 1-year survival rate 53.5%, and the 2-year survival rate 17.9%. Haematological and non-hematogical toxicities were low (CTC-grade 3 neutropenia 14.8%, grade 3 thrombocytopenia 5.2%, grade 3/4 anemia 5.1%, grade 3 nausea/vomiting 5.1%, grade 3 diarrhea 3.6%, grade 3 alopecia 3.6% of pts). The results suggest that the combination of irinotecan (CPT-11) and carboplatin is active and well tolerable in patients with limited disease SCLC who were not suitable for concurrent chemotherapy.