Purpose: To compare and analyze the effect of different clinical target volumes (CTVs) on survival rate after postoperative radiotherapy (RT) for esophageal squamous cell carcinoma (SCC). Methods and Materials: We studied 102 patients who underwent postoperative RT after radical resection for esophageal SCC (T3/4 or N1). The radiation dose was >= 50 Gy. In the extensive portal group (E group, 43 patients), the CTV encompassed the bilateral supraclavicular region, all mediastinal lymph nodes, the anastomosis site, and the left gastric and pericardial lymphatic. In the regional portal group (R group, 59 patients), the CTV was confined to tumor bed and the lymph nodes in the immediate region of the primary lesion. The 1-, 3-, and 5-year survival rates were compared between the groups, and multivariate/univariate analysis for factors predicting survival was studied. Results: For the entire group, the 1-, 3- and 5-year survival rates were 76.3%, 50.5%, and 42.9%, respectively (median survival, 30 months). The 1-, 3-, and 5-year survival rates were 76.5%, 52.1%, and 41.3%, respectively, in the E group and 76.2%, 49.2%, and 44.6%, respectively, in the R group (not significant). According to the multivariate analysis, N stage, number of lymph nodes with metastatic disease, and tumor length were the independent prognostic factors for survival. Conclusions: Using a regional portal in postoperative RT for esophageal SCC is not associated with compromised survival compared with extensive portal RT and therefore should be considered. N stage, number of affected lymph nodes, and tumor length predict poor survival. (C) 2008 Elsevier Inc.