This study was conducted to determine the effects of immediate enteral nutrition (EN) on nutritional status, immunological competence, and the suppression of excessive inflammatory responses in patients following esophageal cancer surgery. Twenty-four patients who underwent the same elective operation for thoracic esophageal carcinoma were randomized into an immediate enteral nutrition (IEN) group who received EN from postoperative day (POD) 1 and a parenteral nutrition (PAN) group. Both groups received comparable volumes and calories on the same POD. Laboratory studies were carried out preoperatively and on PODs 1-7. Other nutritional and immunological assessments were repeated on PODs 1 and 7. Plasma concentrations of nitrate and nitrite were also measured. All of the patients in the IEN group tolerated enteral feeding well. There were no significant differences in the results of nutritional assessments, lymphocyte function, or plasma nitrate and nitrite levels between the two groups. The IEN group showed a significantly earlier recovery of the total lymphocyte count. The serum levels of total bilirubin and C-reactive protein were significantly attenuated in the IEN group. These results indicate that immediate EN may have beneficial effects on immunological competence and the suppression of excessive inflammatory responses in patients following esophagectomy. Patients undergoing radical esophageal surgery who are subjected to severe surgical stress might benefit the most from early EN.