Objectives：Weight loss and malnutrition in patients undergoing radiotherapy for head and neck cancer are usual and preventable. The effect of nutritional support with oral high protein liquid was evaluated. Material and Methods：From Feb. to Dec. 2007, twenty patients received nutritional supplement with oral high protein liquid during radiotherapy for head and neck cancer and the nutritional status was evaluated. Weight loss was compared with control group of similar clinical characteristics. Results：Nutritional parameters such as weight, arm circumference, hemoglobin, hematocrit, total protein, albumin, transferring and the number of lymphocyte were relatively well maintained in patients with nutritional support with oral high protein liquid. In addition weight loss was minimal and significantly lower compared with control group. Conclusion：Nutritional support with oral high protein liquid was effective on maintaining nutritional status for the patients with head and neck cancer during radiotherapy.