Background : Definitive chemoradiotherapy (dCRT) is one of the treatment options for stage II/III esophageal squamous cell carcinoma (ESCC). RTOG9405 demonstrated that a higher dose of radiation (64.8 Gy) offered no additional survival benefit over the standard dose (50.4 Gy). We compared the long-term outcomes of dCRT with radiation doses of 60 Gy and 50.4 Gy for ESCC. Methods: Selection criteria included thoracic ESCC, stage II/III (non T4), performance status (PS) 0-2, age 20-75 years, adequate organ function and no other active malignancy. We retrospectively analyzed patients who received dCRT as a first-line therapy between Jan. 2000 and Nov. 2011 in our hospital. Group A (n = 180) received 2 cycles of cisplatin (C) (40 mg/m² on day 1 and 8) with fluorouracil (F) infusion (400 mg/m²/day on day 1-5 and 8-12), or 2 cycles of C (70 mg/m² on day 1) with F infusion (700 mg/m²/day on day 1-4) repeated every 4 weeks and concurrent radiotherapy at a dose of 60 Gy. Group B (n = 62) received 2 cycles of C (75 mg/m² on day 1) with F infusion (1000 mg/m²/day on days 1–4) repeated every 4 weeks and concurrent radiotherapy at a dose of 50.4 Gy. Overall survival (OS) and progression free survival (PFS) were estimated with the Kaplan-Meier method and compared with log-rank test. The Cox regression model was used for multivariate analysis to assess the prognostic factors for OS. Results: Characteristics of both groups were as follows (Group A: Group B): median age, 64:62; male/female, 154/26:55/7; PS 0/1/2, 81/98/1:46/16/0; T1/2/3, 39/27/114:19/9/34; N0/1, 41/139:6/56. Median follow-up period was longer than 40 months for both groups. 5-year survival rates were 44.5% for Group A and 60.0% for Group B. Median PFS and median OS were 16.5 months and 36.2 months for Group A, 41.1 months and 98.3 months for Group B. By multivariate analysis, Group B (hazard ratio [HR] 0.617: 95% confidence interval [CI]:0.400-0.951, p = 0.029), T1/2([HR] 0.383: 95% [CI]: 0.260-0.566, p < 0.001) were significant prognostic factors for OS. Conclusions: CRT with 50.4 Gy showed better long-term survival than with 60 Gy.