Gastrointestinal endoscopy is an increasingly important method for diagnosis and treatment of disease. This atlas demonstrates endoscopic findings in a variety of gastrointestinal infectious, inflammatory, vascular, and neoplastic conditions. Cancer screening and prevention are common indications for gastrointestinal endoscopy, and the premalignant conditions of Barrett’s esophagus and colonic polyps are illustrated. Endoscopic treatment modalities for gastrointestinal bleeding, polyps, and biliary stones are demonstrated in video clips. The images shown in this atlas are also found in Chap. 315 of the book.