Objective The indications for endoscopic treatment in early stage cancer of the digestive tract are expanding with the emergence and technical development of endoscopic submucosal dissection (ESD). ESD requires longer term stable sedation than conventional endoscopic procedures due to the necessity of meticulous control of the devices during the procedure. Propofol has a very short half-life and can be administered continuously, which is advantageous for long-term sedation. Propofol, thus, is likely to be useful for sedation during ESD. Methods Fifty consecutive patients who underwent ESD for early gastric cancer with propofol sedation (Group P) and those with midazolam sedation (Group M) were included in this study. Cardiorespiratory suppression rate and the condition of arousal were compared between the groups. A questionnaire survey on the satisfaction of endoscopists, anesthesiologists, endoscopy nurses, and ward nurses with the use of propofol was also carried out. Results Respiratory suppression was observed in 50% in Group M and in 20% in Group P (p<0.05). Hypotension was seen in 14% and 36% in Groups M and P, respectively (p<0.05). No sedation-related complications were encountered in either of the groups. Arousal rates 1 hour and 3 hours after the procedure were 23% and 60% in group M and 86% and 100% in Group P (p<0.05). As for the questionnaire survey, most respondents, in particular the ward nurses, supported the use of propofol. Conclusion Our data suggest that propofol is safe and useful during ESD as compared with midazolam.