Extensive lymphadenectomy, including upper mediastinum, for thoracic esophageal carcinoma was introduced at the beginning of 1980s. However, the efficacy has not been analyzed in large series at a single institute. We evaluated factors potentially related to improved surgical results in patients with thoracic esophageal squamous cell carcinoma (SCC). From 1959 to 1998, a total of 792 patients with thoracic esophageal SCC underwent R0 surgery. A variety of clinicopathological factors were compared among patients treated from 1990 to 1998 (recent group, n=164) and 1959 to 1989 (former group, n=628). The recent group showed significantly better survival than the former group (5-year survival rates: 51 versus 17%, P<0.01), partly because earlier stage disease was included in the recent group than in the former group. Multivariable analysis, using the Cox regression analysis, indicated the time period of surgery, age, tumor location, the number of positive nodes (>5), venous invasion, and tumor-node-metastasis stage. Upper mediastinum lymphadenectomy was also an independent factor to improve survival of patients with thoracic esophageal SCC.