A multicenter Phase II study was performed by the AIRO-Lombardia Cooperative Group on 36 patients with Stage III non-small cell lung cancer. The treatment schedule included hyperfractionated radiotherapy, 1.2 Gy twice daily (5 days/week) up to a total dose of 69.6 Gy, and concomitant cisplatin by continuous infusion using a portable pump, 16 mg/m2/week for 6 weeks. Overall, adequate treatment (defined as a total dose > 66 Gy in < 46 days and 6 weeks of infusional cisplatin) was received by 56% of accrued patients. Response was complete in 6% and partial in 56% of patients; median survival was 8 months and 1-year survival rate was 37%. Site of first failure was local in 43%, distant in 43%, local and distant in 10% and unknown in 3% of failing patients. Grade 3 esophagitis was recorded in 14% of patients and a fatal case of late pulmonary toxicity was reported. On the basis of feasibility, toxicity and survival results, the planned extension to Phase III was abandoned by the Group.