Background and Study Aim: Recently endoscopic submucosal dissection (ESD) for early gastric neoplasms became widespread in Japan. However outcomes of ESD had not been distinct because previous reports had limitations of advanced single center studies. Aim of this study is to clarify the standardized outcomes of ESD for early gastric neoplasms in a multicenter questionnaire study. Methods: A questionnaire was conducted by the Nagano ESD study group for 31 centers in Nagano prefecture in Japan and 30 centers (96.8%) replied. Contents of the questionnaire included outcomes and complications. Early gastric cancer (EGC) was divided into three categories based on pathological diagnosis following gastric cancer treatment guidelines of the Japanese gastric cancer association: Standard indication(SI); differentiated adenocarcinoma, intramucosal cancer ≦20 mm in size, Expanded indication (EI); differentiated adenocarcinoma, intramucosal cancer regardless of tumor size without ulcer findings, intramucosal cancer ≦30 mm in size with ulcer findings, minute submucosal cancer (sm1) ≦30 mm in size, Out of indication (OI); except for the above. Results: A total of 715 early gastric neoplasms (586 EGCs, 129 gastric adenomas) were treated in all centers with ESD from January to December 2005. The rates of en-bloc and cut end negative resection of EGCs of SI, EI and OI were 91.6% (295/322), 84.8% (151/178) and 81.3% (71/86), respectively. The reasons for impossibility of en-bloc and cut end negative resection were as follows; In SI group, piecemeal resection accounted for 29.6% (8/27), positive lateral margin 59.2% (16/27), positive horizontal margin 11.1% (3/27); in EI group, piecemeal resection 59.2%(16/27), positive lateral margin 29.6% (8/27), positive horizontal margin 11.1% (3/27); in OI group, piecemeal resection 20.0%(3/15), positive lateral margin 33.3% (5/15), positive horizontal margin 46.7% (7/15). Incidence of perforation was 4.06% (29/715). Incidence of bleeding that required blood transfusion was 0.28% (2/715). All complications were managed endoscopically and there was no procedure related mortality. Conclusions: In this multicenter retrospective study, standardized outcomes of ESD were excellent and complications were tolerable in comparison with advanced single center reports.