Synchronously administered cis-platinum (cis-DDP) and radiation therapy have been used to treat unresectable squamous cell carcinomas of the head and neck. The purpose of this study was to evaluate the efficacy and tolerance of preoperative adjuvant cis-DDP plus radiation therapy in operable stage III and IV head and neck cancers. Radiation therapy (4,500 rad) was delivered in 180-rad daily fractions. Cis-DDP (20 mg/M2) was given before radiotherapy on days 1-4 and 21-24. Eighteen patients began therapy; 16 completed the combined regimen. Toxicity included stomatitis and WBC below 2,500/mm3. One patient died from therapy of a cerebrovascular accident. Sixteen patients (89%) achieved a complete or partial response to therapy. Complete responses were observed in 13 of 18 primary tumors (72%), and in all three patients with cervical lymphadenopathy. Complete responses were noted for lesions of the nasopharynx, oral cavity, pharynx, hypopharynx, and larynx, for all histologic grades of squamous cell carcinoma. Twelve patients underwent curative surgery. Site-related morbidity occurred in two patients (15%) and a third patient developed postoperative pneumonia. Five of 10 resected primary tumors with preoperative complete responses were pathologically negative for tumor. Concurrent bolus cis-DDP and radiation therapy are well-tolerated and result in impressive tumor reduction. Morbidity after subsequent curative surgery is low, and histologic complete responses are frequent.(ABSTRACT TRUNCATED AT 250 WORDS)