From July 1989 to July 1991, 73 previously untreated patients with histologically proven stage III inoperable non-small cell lung cancer have been treated with standard fractionation radiation therapy and concomitant cisplatin by continuous infusion. Thoracic irradiation was delivered at a dose of 40 grays in 20 fractions over 4 weeks to the entire mediastinum, ans was followed after a two-week rest by a boost of 30 grays in 15 fractions over 3 weeks with oblique fields sparing the spinal cord. Continuous infusion cisplatin was given during the second week or each radiation therapy sequence at a dose of 20 mg/sqm/24 hours during five days (120 hours) with usual hyperhydratation and antiemetic measures. Toxicity was essentially hematologic and gastro-intestinal but there was only 4.1% grade 3 or grade 4 complications. Radical surgery became feasible after the first cycle of treatment in 10 patients (13.7%). Complete response rate as determined by CT-scan and fiberoptic bronchoscopy was 61.6%. At a median follow-up of 26 months, actuarial overall survival at 1, 2 and 3 years was 46.6%, 27.7% and 24.5%, respectively. There were no local recurrence or distant relapses after 3 years, which will hopefully result in long-term survival in one quarter of these patients. These results compare favorably with other studies combining radiation therapy and concomitant cisplatin with different dosage and schedule. Local control appears substantially improved by this combined modality treatment over radiation therapy alone. However, the incidence of distant metastasis remains significant, especially during the first year of follow-up. Further improvement of early and long-term survival could possibly result from the incorporation in this protocol of a second drug active against subclinical dissemination.