Purpose This study evaluated the effectiveness and safety of intensity-modulated radiation therapy (IMRT) for locally advanced esophageal squamous cell carcinoma (ESCC). Methods Between August 2009 and December 2011, 112 patients with pathologically confirmed ESCC treated with IMRT at Jiangsu Province People's Hospital and Nantong Tumor Hospital were included in a retrospective analysis. Patients received either IMRT alone (group A) or concurrent chemoradiotherapy (CRT) (group B). A radiation dose of 60–66 Gy administered in 30–33 fractions was delivered to the tumor. The patients in group B simultaneously received 2 cycles of cisplatin-based doublets with either 5-fluorouracil or taxotere. The Kaplan-Meier method was used to compute the survival time. Early and late toxicities were scored according to CTCAE v.3.0. Results The response rate of group B (91.07%) was not significantly greater than that of group A (89.29%) (X² = 0.10, p = 0.75). The 1- and 3-year survival rates of group B (87.5% and 57.14%, respectively) were greater than those of group A (69.64% and 37.50%, respectively). The difference in overall survival was statistically significant between groups A and B (x² = 5.30, p = 0.02; x² = 4.33, p = 0.04). Hematological toxicity, gastrointestinal toxicity, and treatment-related esophagitis were significantly higher in group B than group A (16.07% vs. 33.93%, p = 0.04; 10.71% vs. 26.79%, p = 0.03; 19.64% vs. 44.64%, p = 0.01). However, intergroup differences in terms of late toxicity were not significant. Conclusions IMRT was a practical and feasible technique to treat ESCC. Concurrent CRT could increase local tumor control and long-term survival. The CRT regimen was associated with a higher incidence of acute gastrointestinal and hematological toxicity.