Endoscopic submucosal dissection (ESD) is a new endoscopic resection technique introduced after endoscopic mucosal resection (EMR) by which the endoscopist can remove a superficial gastrointestinal neo plasm. The endoscopist can determine the incision line preoperatively and can resect even relatively large mucosal tumors en bloc using the ESD technique. ESD has four steps: marking around the lesion, submucosal injection, circumferential incision of the mucosa, and finally dissection of the submucosal layer. ESD requires specific endosurgical knives that are divided into two basic types, the tip-covered type and the tipnoncovered type. The drawbacks of ESD are that it is more time consuming and has a higher rate of compli cations (bleeding and perforation) compared with EMR. These problems are being overcome gradually with advances in devices and endoscopist skill. The indication for ESD has been extended to not only gastric neoplasia but also esophageal and colonorectal neoplasia.