Iintroduction: Early radiotherapy concurrent with chemotherapy appears to have prognostic benefits in patients with limited disease SCLC. Irinotecan/cisplatin have been shown to be superior to a standard treatment with etoposide/cisplatin in extensive disease SCLC. The present phase I study aims to assess the feasibility of irinotecan/cisplatin administered concurrently with radiotherapy. Patients and methods: Twelve patients were treated concurrently with conventional fractionated radiotherapy (1.8-45Gy + 9Gy (RP)) and two cycles of irinotecan (40/50/60 mg/m(2), Day 1/8/15, 29/36/43) and cisplatin (20 mg/m(2), Days 1-3, 29-31), and four cycles of consolidation chemotherapy (CT). In addition, patients in complete remission (CR) received prophylactic cranial irradiation (PCI). Dose-limiting toxicity (DLT) was defined as any case grade III/IV non-hematological toxicity (esophagitis grade IV), grade IV leukopenia or grades III/IV thrombopenia (CTC) during RCT. Results: No DLT was observed; an irinotecan dose of 60 mg/m(2) is recommended. 3/12 patients developed grade III leukopenia, one grade 11 pneumonitis. The predominant toxicity was esophagitis, grade II in 7/12 patients, grade III in 5/12. After RCT 7/12 patients were in CR, systemic progression was not observed during RCT. Conclusion: Concurrent RCT with irinotecan (60 mg/m(2)) and cisplatin followed by four cycles of CT can be safety administered. (C) 2006 Elsevier Ireland Ltd. All rights reserved.