Endoscopic submucosal dissection (ESD) is a technically difficult and time-consuming procedure. Several water-jet knives have been developed to address this issue. The aim of this study was to develop a new ESD method using continuous low-pressure water injection at 1-2 atmosphere with a tip-injected electric knife while dissection simultaneous cutting, dissection, electrocoagulation, and hemostasis, which was so called as submucosal pressure ejection endoscopic dissection (SPEED) to treat early gastric cancer and compare the efficacy and safety with conventional methods.