Introduction: Nutritional intervention is a very important component of the care of patients with head and neck cancer. We aimed to evaluate an early implemented and individualized protocol of nutritional support in head and neck cancer patients submitted to radiotherapy alone or combined chemoradiotherapy. Material and methods: We studied 43 head and neck cancer patients who received radiotherapy or chemoradiotherapy. Every patient was evaluated by an expert dietician at baseline and then twice a week after completion of treatment. The indication for oral supplements was a <65% of daily intake of the total estimated daily calorie needs. The indication for enteral nutrition through gastrostomy or nasogastric tube was the presence of severe dysphagia, making the oral route impossible. Results: Less than one-fifth of the patients were well-nourished, and more than one-fourth presented severe malnutrition at baseline. Changes in nutritional parameters during follow-up with the employed nutritional support showed a loss of only 2.12±2.9 kg of body weight (p<0.001), 0.70±0.20 kg/m2 of body mass index (p=0.001), 0.82±1.26 mm of triceps skinfold (p=0.003), and 0.12±1.42 cm of midarm circumference (p=0.786). No significant differences were found in serum albumin, prealbumin or retinol-binding globulin levels. When comparing patients treated with radiotherapy alone (n=22) and those treated with chemoradiotherapy (n=21), we found no differences in the aforementioned parameters. Less than one-third needed enteral nutrition by nasogastric tube or gastrostomy. Conclusions: Nutritional screening and intervention with close follow-up is effective in patients with head and neck cancer in order to ameliorate further protein-energy malnutrition.