The value of endoscopy in dysphagia is limited in the diagnosis of motility disorders and small structures, webs, and hiatal hernias. Endoscopy is of special use for the clarification of an organic cause of dysphagia. Intraluminal tumors can be seen and in a high percentage of cases be definitely diagnosed by taking biopsies; a malignant degeneration in Barrett's esophagus is detectable by endoscopy in 89.1% of cases. Gastroesophageal reflux disease can be diagnosed on endoscopy as it leads to an endoscopically visible inflammatory reaction; however, normal findings on endoscopy cannot exclude reflux disease. Endoscopy is the method of choice in the diagnosis of nonreflux esophagitis, especially Candida and viral esophagitis. A further advantage of endoscopy is the fact that a microscopic diagnosis can be obtained and endoscopic treatment can be performed simultaneously. Submucosal or extramural lesions can be missed by endoscopy. Endosonography, the combination of endoscopy and ultrasonography (EUS) yields additional information in diagnosing submucosal and extramural lesions of the esophagus which is missed by other imaging procedures. One of the main advantages of EUS is the detection of small and submucosal lesions. The most important indication is the local staging of esophageal carcinomas; the accuracy of endosonography in determining the depth of infiltration ranges between 79% and 92%. The detection of paraesophageal lymph nodes is successful in 60%-82%, although EUS cannot differentiate benign from malignant lymph nodes. Submucosal tumors can be visualized by endosonography and their size, echopattern, and the layers of origin can be determined with high accuracy. Further indications for EUS are the exclusion of focal lesions in achalasia or peptic strictures.