A synergism between cis-platinum (CDDP) and radiotherapy (RT) has been demonstrated both in culture systems and in clinical studies. On the above basis, we planned, in patients with locally advanced or unresectable squamous cell carcinoma of the head and neck, a concomitant treatment with CDDP 80 mg/m2 i.v. every 3 weeks for three doses (days 1,21 and 42) and RT in the primary and in the neck nodes bilaterally, for a total dose of 60–70 Gy. Thirty-five untreated patients with poor prognosis unresectable stage II and stages III-IV disease were entered in the study and 32 were evaluable. Complete response (CR) rate was 75% (24/32) with 95% confidence limits from 60 to 90% (± 15%); 8 cases (25%) achieved a partial response, for an overall response rate of 100%. A significantly higher CR rate and a longer survival rate was observed in patients with good performance status (PS = 90–100) and stages II–III. The overall estimated 2-year survival is 46%; 59% for patients who obtained a CR versus 0% for those who achieved only a partial response. Overall the treatment was well tolerated and gastrointestinal and hematologic toxicities were the most common side effects. In conclusion, the combination of CDDP plus RT is a very effective and safe treatment and we recommend such an approach in head and neck squamous cell carcinoma, particularly in those patients with good PS and with unresectable stage II or stage III disease.