AIM to compare the efficacy and safety of a hook knife(HO) with a hybrid knife(HK) during endoscopic submucosal tunnel dissection(EStD) procedure.METHODS Between August 2012 and December 2015, the ESt D procedure was performed for 83 upper GI submucosal lesions, which originated from the muscularis propria layer identified by upper endoscopy and endoscopic ultrasonography. Of these, 34 lesions were treated by a HO, whereas 49 lesions were treated by a HK. Data regarding age, gender, presenting symptoms, tumor location and size, procedure time, complications, en bloc resection rate and others were analyzed and compared between the two groups.RESULTS there were no significant differences in the age, gender, presenting symptoms and tumor location between the two groups. EStD was successfully completed in all the patients, and no case was converted to laparoscopy. the mean procedure time was significantly shorter in the HK group than in the HO group(41.3 ± 20.3 min vs 57.2 ± 28.0 min, p = 0.004). the mean frequency of device exchange was 1.4 ± 0.6 in the HK group and significantly less than 3.3 ± 0.6 in the HO group(p < 0.001). the differences in tumor size and histopathological diagnoses were not significant between the two groups(p = 0.813, p = 0.363, respectively). Both groups had an equal en bloc resection rate and complete resection rate. Additionally, the complication rate was similar between the two groups(p = 0.901). During the follow-up, no recurrence occurred in either group.CONCLUSION We demonstrate for the first time that HO and HK do not differ in efficacy or safety, but HK reduces the frequency of device exchange and procedure time. AIM to compare the efficacy and safety of a hook knife (HO) with a hybrid knife (HK) during endoscopic submucosal tunnel dissection (EStD) procedure. METHODS Between August 2012 and December 2015, the ESt D procedure was performed for 83 upper GI submucosal lesions, which originated from the muscularis propria layer identified by upper endoscopy and endoscopic ultrasonography. Of these, 34 lesions were treated by a HO, and 49 were were treated by a HK. Data regarding age, gender, presenting symptoms, tumor location and size , procedure time, complications, en bloc resection rate and others were analyzed and compared between the two groups .RESULTS there were no significant differences in the age, gender, presenting symptoms and tumor location between the two groups. EStD was successfully completed in all the patients, and no case was converted to laparoscopy. the mean procedure time was significantly shorter in the HK group than in the HO group (41.3 ± 20.3 min vs 57.2 ± 28.0 min, p = 0.004). The mean frequency of device exchange was 1.4 ± 0.6 in the HK group and significantly less than 3.3 ± 0.6 in the HO group (p <0.001). The differences in tumor size and histopathological diagnoses were not significant between the two groups Both groups had an equal en bloc resection rate and complete resection rate. Additionally, the complication rate was similar between the two groups (p = 0.901). During the follow-up, no recurrence occurred in either group. CONCLUSION We demonstrate for the first time that HO and HK do not differ in efficacy or safety, but HK reduces the frequency of device exchange and procedure time.