The nutritional state of 99 patients with tumors in the head and neck area was determined prior to, during and after radiotherapy by anthropometric, laboratory-chemical and immunological parameters. In 73 orally nourished patients, the nutritional parameters deteriorated very quickly during radiotherapy and recovered slowly and incompletely after radiotherapy. In 26 patients treated prospectively by percutaneous endoscopically guided gastrostomy (PEG), however, an improved nutritional state was achieved already during the irradiation in spite of a less favorable starting point. The subjective feeling of patients was questioned by means of the "quality of life" index according to Padilla et al. (1983). The preliminary results show an identical deterioration of the subjective feeling in both groups, but - as opposed to the other patients - force and working capacity did not decrease during radiotherapy in the enterally nourished patients. This corresponds to the objective nutritional parameters. However, an improvement of the subjective feeling after the end of radiotherapy was observed only in the orally nourished patients. Possible reasons are discussed. We have the opinion that an early and constant enteral nutrition by PEG can stabilize the nutritional state of patients with tumors in the head and neck area. Therefore we recommend to establish a prophylactic, pretherapeutic PEG if an aggressive multimodal therapy is planned, especially in case of apparent primary malnutrition.