Conventional techniques of endoscopic mucosal resection (EMR) by snare resection do usually not achieve resection of gastrointestinal mucosal neoplastic lesions larger than 1 cm in diameter in a single piece ("en-bloc"). En-bloc resection can even fail in cases of smaller lesions depending on their location and shape. Extension of EMR by piecemeal resection is therefore frequently required for removal of the targeted neoplastic area. However the histological evaluation of several specimen can usually not identify the outer margins of the neoplastic area. Thus complete R0 resection cannot be histologically confirmed. Histologically important additional information, e.g. infiltration of lymphatic vessels or submucosal infiltration may be missed in between resected specimen due to coagulation artifacts or left tissue bridges. In addition piecemeal EMR of early neoplasia in Barrett`s esophagus is associated with a high recurrence rate probably because of minor remnants of neoplastic tissue. In contrast to EMR the technique of endoscopic submucosal dissection (ESD) allows en-bloc resection even of large neoplastic lesions. Variations of this method have been increasingly used for various types of early gastrointestinal neoplasia mainly in Asian countries. In Japan ESD has been approved for treatment of selected cases of early gastric and colorectal neoplasia as an alternative to surgery. A recent meta-analysis of non-randomized controlled trials showed that ESD of early gastrointestinal tumors is superior to EMR in terms of en-bloc resection and curative resection rates but it is more time-consuming and is associated with higher rates of bleeding and perforation. A few small series on ESD were also reported from Western countries.