Twenty-three patients with head and neck cancer were randomly allocated, regardless of pretreatment nutrition status, to receive either radiotherapy alone (12 patients) or radiotherapy plus nutritional oral supplementation (11 patients) with high-protein nutritional powder of balanced nutrient content (Ensure). Nutrition status was assessed subjectively and objectively for all patients before and at weekly intervals during the course of irradiation. All patients who received nutritional supplementation experienced an increase in body weight and in triceps skin-fold thickness, whereas 58% of the other group had weight loss (p = 0.001). Irradiation had to be suspended in 5 of the 12 patients who received no nutritional support because of severe mucosal reaction and/or poor performance status. All patients who received nutritional supplementation during radiotherapy had their course of irradiation without interruption.