A total of 14 patients with locally advanced and unresectable head and neck (SCCHN) or non small cell lung cancer were treated with a definitive course of radiation therapy with conventional fractionation and 30 mg/m2 carboplatin (CBDCA) given daily as an i.v. infusion during the 1st, 3rd, 5th and 7th weeks of the combined treatment. The planned tumor dose of at least 7000 cGy was reached in all SCCHN patients except 1 (6600 cGy). The 2 NSCLC patients received 6320 and 5980 cGy, respectively. The planned total CBDCA-dose of 600 mg/m2 was administered in all patients. No treatment delays were required in 10 patients. Interruptions for severe mucositis or myelosuppression occurred in 4 patients (28.6%), but in no case did the delay exceed 1 week. Complete response was obtained in 8 patients (57.1%); 7 of the 12 with SCCHN and 1 of the 2 with NSCLC. The other 6 patients achieved a partial response. Granulocytopenia of WHO grade 3 occurred in 1 patient; apart from vomiting and mucositis, toxicities above grade 2 were not observed.