['Endoscopic submucosal dissection (ESD) is a new technique for endoscopic resection of early-stage gastrointestinal cancers. Though ESD achieves high rate of en bloc resection, it is technically difficult to master. The development of a novel robotic endoscopic system that has 2 arms attached to an ordinary endoscope-Master and Slave Transluminal Endoscopic Robot (MASTER)-has improved the performance of complex endoluminal procedures. We evaluated the efficacy of MASTER-assisted ESD in treatment of patients with early-stage gastric neoplasia.', 'We performed a multicenter prospective study of 5 patients with early-stage gastric neoplasia, limited to the mucosa. After markings and circumferential mucosal incision, all submucosal dissections were performed using the MASTER system. We measured baseline demographics, tumor characteristics, and perioperative and clinical outcomes.', 'All patients underwent successful MASTER-assisted ESD. The mean submucosal dissection time was 18.6 minutes (median, 16 minutes; range, 3-50 minutes). No perioperative complications were encountered. Three patients were discharged from the hospital within 12 hours and 2 on the third day after the procedures. Two patients were found to have intramucosal adenocarcinoma, 1 had high-grade dysplasia, 1 had low-grade dysplasia, and 1 had a hyperplastic polyp. The resection margins were clear of tumors in all 5 patients. No complications were observed at the 30-day follow-up examination. Follow-up endoscopic examinations revealed that none of the patients had residual or recurrent tumors.'] Is robot-assisted endoscopic submucosal dissection effective in treating patients with early-stage gastric neoplasia?