We compared the nutritional condition, immunological function, and frequency of adverse effects during concurrent chemoradiotherapy for oral cancer between patients simultaneously receiving enteral hyperalimentation (Racol) (n=20; EHA group) and patients receiving peripheral vein nutrition (n=20; PVN group). Although there was no significant difference in the change of body weight between the two groups, the decrease of plasma albumin values in the EHA group appeared later than in the PVN group. In the PVN group, the number of lymphocytes and lymphocyte blastogenesis significantly decreased on and after day 14. On the other hand, in the EHA group, the number of lymphocytes decreased only on day 14 and no decrease in lymphocyte blastogenesis was observed. While stomatitis developed in all patients, the severity was lower in the EHA group than the PVN one. These results suggest that the simultaneous administration of Racol during concurrent chemoradiotherapy for oral cancer inhibits the deterioration of nutritional and immunological conditions as well as the severity of stomatitis. This nutrient therapy is therefore considered to be a supportive therapy for oral cancer patients.