To improve the prognosis of limited stage small cell lung cancer (LS-SCLC) the addition of concurrent thoracic radiotherapy to a platinum-containing regimen is important. In the Netherlands, we initiated a multicenter, phase II study, of the combination of four cycles of carboplatin (AUC 5), paclitaxel (200 mg m-2) and etoposide (2 x 50 mg orally for 5 days) combined with 45 Gy (daily fractions of 1.8 Gy). The radiation was given to the involved field and concurrently with the second and third chemotherapy cycle. Patients with a partial or complete response received prophylactic cranial irradiation to a dose of 30 Gy. From January 1999 to December 2001, 37 of the 38 patients with LS-SCLC entered were eligible for toxicity analysis and response. Grade 3 and 4 haematological toxicity occurred in 57% (21/37) with febrile neutropenia in 24% (9/37). There were no treatment-related deaths or other grade 4 toxicity. Grade 3 toxicities were oesophagitis (27%), radiation pneumonitis (6%), anorexia (14%), nausea (16%), dyspnea (19%) and lethargy (22%). The objective response rate was 92% (95% confidence interval (CI) 80-98%) with a median survival time of 19.5 months (95% CI 12.8-29.2). The 1-, 2- and 5-year survival rate was 70, 47 and 27%, respectively. In field local recurrences occurred in six patients. Distant metastases were observed in 19 patients of which 13 in the brain. This study indicates that combination chemotherapy with concurrent involved-field radiation therapy is an effective treatment for LS-SCLC. Despite PCI, the brain remained the most important site of recurrence.