Combined chemoradiotherapy (CT/RT) treatments appear to yield better results for advanced tumours of the head and neck than do conventional therapies. In the present study, CT/RT was used preoperatively in unresectable tumors of the oral cavity and oropharynx. Forty patients were entered prospectively into a phase II study. Treatment consisted of three cycles of chemotherapy with cisplatin and 5-day infusion of fluorouracil (FU), and the addition of simultaneous radiotherapy (30 Gy) from the second to third cycles. Patients with resectable residual disease or complete clinical response underwent surgery. All patients later received a second phase of irradiation (30 Gy) and two cycles of chemotherapy only in responders. During the first phase of treatment, 22 (55%) patients presented mucositis grades III-IV. Mean weight loss was 7%. Twelve patients were admitted for parenteral nutrition. Thirty-six (90%) patients obtained clinical response, which was complete in 15 (37%). Thirty-two of the 40 underwent surgery. The percentage of pathologic complete responses (PCR) was 35% (14 patients). With a median follow-up of 21 months, the median survival of patients was 23 months, and 19 (47%) of them are disease-free. A high PCR rate was attained with this treatment regimen. Toxicity was significant, but tolerable with adequate support measures.