Sixty patients with stage I-III esophageal squamous cell cancer treated by definitive radiotherapy (RT) were analyzed for patterns of treatment failure. Patients were treated by external RT alone (n = 45) or in combination with intraluminal RT (N = 15) when suitable, with prescribed total doses ranging from 59.4 to 104.4 Gy. Concurrent chemotherapy consisting of cisplatin and/or 5-fluorouracil was administered to 19 patients. The two-year actuarial survival rate and two-year disease-free survival rate were 29.5% and 18.3%, respectively. Two-year failure rates were 66.5%, 36.9%, and 3.8%, for the esophagus, lymph nodes, and other sites, respectively. Two-year esophageal failure rates for patients with T1-2 (n = 8), T3 (n = 30), and T4 disease (n = 22) were 14.3%, 64.7%, and 87.9%, respectively (p < 0.05). A multivariate analysis of esophageal failure with descriptive variables of T classification, tumor length, and performance of intraluminal RT revealed that only T classification was an independent factor (p = 0.021). Two-year lymph node failure rates were 24.8% and 33.6% for patients with N0 (n = 36) and N1 disease (n = 24), respectively (p = 0.0035). Lymph node failure in N0 patients was found exclusively outside the treatment field. These results suggest that inclusion of potential lymph node metastases in the radiation field could lessen the lymph node failure rate in T1-3N0M0 patients.