A bleeding peptic ulcer is the most common cause of upper gastrointestinal bleeding as well as for hospitalization and death. Many endoscopic methods of treating bleeding peptic ulcers are currently being studied and developed. Among them, the endoscopic pure ethanol injection therapy is favored because of its high efficacy, low cost, and rapid administration. Pure ethanol is an excellent agent to stop bleeding and manifests itslef by inducing tissue dehydration, fixation and vessel compression, which in turn causes arterial coagulation and tissue necrosis. However, an excessive injection volume may bring about extensive mucosal necrosis; hence, caution should be taken when deciding upon the injection volume and depth. We report a case of extensive necrosis of the gastric mucosa following endoscopic ethanol injection therapy of a bleeding peptic ulcer along with a review of the relevant literature. (Korean J Gastrointest Endosc 2008;36:154-158)