To clarify the long-term survival data and factors that are correlated with survival outcome of unresectable locally advanced non-small cell lung cancer (NSCLC) following chemoradiotherapy, we analyzed patients who entered the Japan Clinical Oncology Group (JCOG) clinical trials for unresectable locally advanced NSCLC. Between October 1989 and August 1997, 240 patients (male 207, female 33; PS (performance status) 0 58, PS 1 172, PS 2 9, unknown 1; stage IIB 2, IIIA 62, IIIB 175, unknown 1) entered the 6 trials. All patients received chemotherapy and radiotherapy. The associations between survival outcome and treatment-related factors were analyzed using Cox regression analysis. Median survival times and 5-year survival rates in the trials were 11.9-19.7 months and 0-17.6%, respectively. Median survival time was 16.1 months and the 5- and 7-year survival rates of all 240 patients were 14.4% and 12.0%, respectively. No deaths were observed 7 years after initiation of the treatment or later. For stage IIIA and IIIB patients, the 5-year survival rates were 16.3% and 13.4%, respectively. Node status and age were significantly associated with survival, but no factors of the treatment were associated with survival of patients with unresectable locally advanced NSCLC. The present retrospective analysis showed that approximately 12% of patients with unresectable locally advanced NSCLC could be cured by various chemoradiotherapy regimens.