A patient with an esophageal duplication cyst who presented with dysph
agia is described here. The diagnosis was accurately made preoperative
ly by endosonography due to the demonstration of contiguity of the mus
cularis propria of the esophagus with the muscle layer of the cyst wal
l. Endoscopic ultrasound is the most reliable nonsurgical method for t
he diagnosis of this lesion, assisting in surgical planning in symptom
atic patients and observation in asymptomatic ones.