Radiation esophagitis remains the primary dose-limiting acute toxicity in the radiotherapeutic management of thoracic neoplasms. Improved understanding of this toxicity will facilitate dose escalation and enhancement of the therapeutic ratio. This article reviews the predictive factors and preventive strategies for radiation esophagitis. In particular, clinical and dosimetric studies predicting the risk of radiation esophagitis are analyzed. The critical impact of chemotherapy on radiation esophagitis is characterized. Preventive strategies to minimize this toxicity also are explored. Overall, this article reviews the current understanding of radiation toxicity for the esophagus.