The esophageal cyst result from a wrong cleavage of the primitive gut in the 4 weeks embryo. In embryo and after seperation of the tracheal diverticulum, the esophagus is lined with ciliated cells which are able cover a "cystic duplication". It is often difficult to distinguish between the bronchogenic and the esophageal cyst. Pathological findings showed the presence of a ciliated epithelium without cartilage which was diagnosed as an esophageal cyst. The patient was 21 year old man for evaluation of the cyst in the posterior mediastinum. The cyst was located the intramural esophagus. Microscopically, the cyst was lined with ciliated columnar epithelium and there was no evidence of cartilage. The cyst was confirmed as the intramural esophageal cyst.geal cyst.