A synergism between cisplatin and radiotherapy has been demonstrated in in vitro and in vivo studies. To improve the locoregional control of disease and the survival rate in patients affected by locally advanced or recurrent squamous cell carcinoma of the head and neck, we planned a Phase II study of concurrent radiotherapy, 2 Gy for 5 days every week for a total dose of 60-70 Gy with cisplatin 80 mg/m2 every 21 days for 2 or 3 doses (on days 1, 21, 42). Fifty-one patients were entered in the study; 48 were evaluable for response and toxicity; 18 (37.5%) had untreated Stage III disease; 25 (52%) had Stage IV disease; 5 (10.5%) had recurrent disease. The complete response rate in Stage III-IV patients was 63% (27 of 43) with 95% confidence limits from 48 to 77% (+/- 14.5%). In the group of five patients with recurrent disease, only one (20%) achieved a complete response. In patients with Stage III-IV disease, a significantly higher complete response rate was observed for those younger than 58.5 years (p = 0.05). The overall estimated 1- and 2-year survival was 59% and 37%, respectively, and a significantly better survival was observed in complete responders compared to partial responses or patients with stable disease (p = 0.037). Disease-free survival was 46% and 36% at 1 and 2 years, respectively. Distant failure occurred only in 12.5% of the patients. Overall, the treatment was well tolerated, and only three patients refused to complete the planned therapy. Gastrointestinal and hematological toxicity were the most common side effects. Data from present trial were compared with that of 50 patients with comparable characteristics treated with radiotherapy alone from 1985 to 1987 as a historical control. The complete response rate, the disease-free survival, and the overall survival appear to be better in the patients treated with chemoradiotherapy. It was concluded that the combination of chemoradiotherapy in patients with Stage III-IV head and neck squamous cell carcinoma is an effective and safe treatment with an apparent better locoregional control than radiotherapy alone. Survival results need to be evaluated in a Phase III randomized trial.