In a prospective, randomized, multicenter study, neoadjuvant chemotherapy (CT) with carboplatin and 5-fluorouracil (5-FU) followed by locoregional treatment (LRT) was compared with locoregional treatment alone in the treatment of patients with head and neck cancer. This study, which includes 324 patients, was conducted from January 1988 to July 1991. The aim of this study was to evaluate the impact of the carboplatin/5-FU regimen both on the incidence of mutilating surgery and on the survival rate. Chemotherapy consisted of three cycles of carboplatin 400 mg/m2 day 1 and 5-FU 1 g/m2 days 1-5, repeated every 3 weeks. Patients with a complete tumor response then received radiotherapy alone, instead of the treatment planned initially. Three hundred patients were analyzed: 79 had tumors of the oral cavity, 106 oropharyngeal tumors, and 115 pharyngolaryngeal tumors. One hundred fifty patients underwent CT+LRT; 150 patients had LRT alone. Grade 3 and 4 toxicity rates were minimal in the CT+LRT group; toxicity was mainly hematologic (24% neutropenia, 19% thrombocytopenia). There were 3 toxic deaths (2%), 2 due to septicemia and 1 due to cardiac toxicity. One hundred forty-three patients were evaluable for efficacy. The tumor objective response rate was 63% and complete response rate was 31% (35% for oropharyngeal, 34% for pharyngolaryngeal tumors, 22.5% for oral cavity tumors), which led to a 29% decrease in the rate of mutilating surgery. Conservative treatment was performed in 57% of patients in the CT+LRT group vs. 24% in the LRT group (p = 0.001). There was no significant difference between survival curves in the CT+LRT and LRT groups. At 4 years, overall survival rates were 56 and 46%; disease-free survival rates were 33 and 30% in the CT+LRT and the LRT groups, respectively. The survival rates were not significantly different in the two groups. The locoregional recurrence rates were 35% in the CT+LRT arm and 25% in the LRT arm (p = 0.04), with median follow-up of 25 months. The rates of secondary localization and distant metastasis were not significantly different in the two groups.