Esophagogastroduodenoscopy has become the most accurate diagnostic method for identifying lesions of the upper gastrointestinal (GI) tract. It permits thorough inspection and a direct biopsy yielding a tissue diagnosis of surface lesions from the upper part of the esophagus to the second portion of the duodenum. The surgeon responsible for patients with upper GI tract disease should perform the endoscopic examination to gain first-hand information on the nature, extent, and location of the patient's problem. The surgeon-endoscopist gains an extra advantage, since the size and proximity of a lesion to the cardia, pylorus, or ampulla will determine surgical options available for the patient's problem. In patients with upper GI tract hemorrhage, the surgeon can determine immediately whether the bleeding is due to esophageal varices, Mallory-Weiss tear, gastric erosions, or an ulcer or tumor of the esophagus, stomach, or duodenum.