In the past 20 years, 403 patients with thoracic esophageal carcinoma underwent radical surgery. The aim of this study was to determine whether extended lymph node dissection improved the prognosis of these patients. All of the patients were divided into 4 groups every 5 years from group A to group D. Group A (n = 39) underwent radical esophagectomy with lower mediastinal and abdominal lymphadenectomy by the left thoracoabdominal approach. Majority cases in Group B (n = 94) also underwent radical esophagectomy with right upper, lower mediastinal and abdominal lymphadenectomy (incomplete 2-field dissection) by the right thoraco-abdominal approach. About 40% cases in Group C underwent radical esophagectomy with extended cervicothoraco-abdominal lymph node dissection (3-field dissection) and almost all of the others had radical esophagectomy with 2-field dissection. About 60% of the cases in group D underwent radical esophagectomy with 3-field dissection and the majority of the others had complete 2-field dissection (i.e.) radical lymphadenectomy around bilateral upper, lower mediastinal and abdominal lymph nodes. The five-year survival rate was 21% in group A, 23% in group B, 37% in group C and 55% in group D. The survival curve was improved according to the extent of lymph node dissection. Especially significant improvements of survival rate were found in group C and D compared with those in group A and B. Furthermore, group D showed significantly better survival than that of group C. Complete 2-field and 3-field dissection resulted in a better prognosis than incomplete 2-field dissection, while no significant difference in prognosis was found between complete 2-field and 3-field dissection. However, neither 2-field nor 3-field dissection resulted in improved prognosis in cases involving 7 or more positive lymph node metastases. These results suggest that radical esophagectomy and lymph node dissection involving bilateral upper mediastinal area are important factors to improve postoperative prognosis in patients with thoracic esophageal carcinoma. However, more effective adjuvant therapy is needed for the patients with many positive node metastases.