PURPOSE: Though caustic injury of the upper digestive tract can lead to severe sequelae, there are few clinical studies on this subject. This study was undertaken to evaluate the clinical characteristics, the endoscopic findings and the risk factors of the upper digestive lesions in patient with caustic ingestion injury. METHODS: We retrospectively reviewed the medical records of 137 patients who ingested caustic materials and who visited to our emergency room from January, 2000 to June, 2009. RESULTS: The most common ingested agent was sodium hypochlorite (44.5%), followed by acetic acid (19.7%), hydrochloric acid (11.7%) and lye (8.0%). Ingestion for suicidal attempt (62.0%) was more frequent than accidental ingestion (30.7%). Grade IIa injury was the most frequent finding on endoscopy of the esophagus and Grade I injury was the most frequent finding on endoscopy of the stomach. For the late sequelae, there were 9 cases (6.6%) of esophageal stricture and 2 cases (1.5%) of gastric outlet obstruction. The initial signs and symptoms did not correlate with the development of stricture, but leukocytosis, and grade III injury were related to the risk of developing stricture. CONCLUSION: Caustic injury of the upper gastrointestinal tract is frequently observed on early endoscopy and it can cause significant late sequelae such as stricture. Therefore, it is necessary to evaluate these patients with regular follow up endoscopic examinations for the management of late sequelae.