The combination of daily low-dose carboplatin and radiotherapy was studied in 55 patients with inoperable head and neck cancer. All patients were planned to receive 70 Gy plus carboplatin i.v. daily, 45-60 min before radiotherapy. A starting schedule of 30 mg/m2 on days 1 through 5, weeks 1, 3, 5 and 7 was administered to 17 patients; an escalating daily dose, up to 55 mg/m2, was given to 38 additional patients. Up to a daily dose of 45 mg/m2, only 4.4% of the patients developed grade 3 leukopenia; on the contrary, grade 3 and 4 leukopenia was seen in 62.5% of patients receiving 50 mg/m2 or more. Mucositis was the major nonhaematologic toxicity and seemed to be dose-dependent. At the end of the loco-regional treatment there were 33 (61.1%) CR and 17 PR; the most effective total carboplatin dose seemed to be 40-45 mg/m2. After surgical salvage the number of CRs increased to 37 (68.5%). One- and 2-year loco-regional control rates were 64% and 53% respectively. One- and 2-year actuarial survival rates were 71% and 53% respectively; the corresponding rates of disease-free survival were 60% and 43%. There was a strong correlation nodal status and both survival and disease-free survival.