Nutritional interventions are not routine in patients undergoing oropharyngeal radiotherapy. The aim of the present study was to assess the effects of early nutritional intervention. Forty-five outpatients undergoing radiotherapy for oropharyngeal cancer were prospectively managed by nutritionists (intervention group). In this group, a percutaneous endoscopic gastrostomy (PEG) was inserted before radiotherapy in any patient in whom at least one of the following applied: weight loss >10%; BMI <20 kg/m(2); age >70 years. Data were compared with those recorded in an historical control group of 45 paired patients. A PEG was inserted in 33 (74%) of the 45 patients in the intervention group, as against 5 (11%) of the 45 in the control group ( P<0.001). The mean weight loss and the frequency of hospital admission for dehydration were lower in the intervention group than in the control group ( P<0.01). In conclusion, early nutritional intervention, including PEG insertion, is feasible and efficient in preventing dehydration in oropharyngeal cancer patients undergoing radiotherapy. It may improve quality of life by decreasing the frequency of hospital admissions.