In the EORTC Radiotherapy Group, the feasibility of multiple fractions per day (MFD) was tested in a pilot study from 1978 to 1980. Three daily fractions of 1.6 Gy were given (4 h interval) during 2 weeks (total dose 48 Gy), with a boost to about 70 Gy after 3-4 weeks. In 53 of the 179 patients, misonidazole was given on every irradiation day (1 g/m2, total 13-14 g/m2). Data on tolerance and early treatment results were published previously; results with a minimum follow-up period of 3 years are now available. Survival (actuarial is 21% and locoregional tumor control was obtained in 34% of patients; no significant differences were seen between the subregions in the head and neck area. Survival is better in patients treated with misonidazole (probably due to selection), but locoregional control was identical as in patients treated without the sensitizer. In February 1984, 38 patients were alive, 35 without evidence of local tumor (5 after rescue surgery). Metastases were seen in 16% and a second tumor in 7% of patients. Seventeen patients (9%) died of causes, possibly related to treatment; necrosis was observed in 8 (4 with local tumor). Late effects in the long survivors were comparable to what is usually seen after high-dose radiotherapy.