OBJECTIVE Hyperthermia is now being widely used to treat clinical malignancies especially combined with radiotherapy and more rarely with chemotherapy. The combination of heat, radiation, and chemotherapy (trimodality) can lead to potent interaction. The present Phase I-II study was conducted to evaluate the feasibility and acute toxicity of a combination of cisplatin, hyperthermia, and irradiation in the treatment of superficial cervical nodal metastases from head and neck cancer. METHODS Eighteen patients with measurable neck metastases from previously untreated squamous cell head and neck tumors were entered into the trial. Therapy consisted of a conventional irradiation (total dose 70 Gy, 2 Gy five times a week) combined with a weekly administration of 20 mg/m2 iv of cisplatin and a total of two sessions of local external microwave hyperthermia (desired temperature of 42.5 degrees C for 30 min). RESULTS Feasibility of the treatment was demonstrated. Acute local toxicity was mild; no thermal blisters or ulcerations were reported and only two patients experienced local pain during hyperthermia. Cutaneous toxicity appeared greater than in our previous studies with irradiation plus hyperthermia and irradiation plus cisplatin. Systemic toxicity was moderate with major toxic effects observed in three patients (World Health Organization (WHO) grade 3 anaemia). Even though it was not an aim of the study to evaluate the nodal response, we observed a complete response rate of 72.2% (95% confidence interval 51-93.4%), 16.6% of partial response and 11.1% of no change. CONCLUSIONS The study confirms the feasibility of the combination of cisplatin, heat, and radiation with an acceptable toxicity profile. The trimodal therapy deserves further evaluation as a way to enhance the efficacy of irradiation in the treatment of nodal metastases from head and neck tumors.