Abstract:[Objective] To compare the clinical outcomes of percutaneous endoscopic interlaminar discectomy (PEID) with the Delta en- doscopy versus the counterpart through the Quadrant channel for large L5S1 disc herniation in young adults. [Methods] A retrospective study was performed on 62 young patients who underwent minimally invasive surgery for the giant L5S1 disc herniation in our department from Janu- ary 2018 to December 2020. According to the results of preoperative doctor-patient communication, 27 patients received the endoscopic dis- cectomy (ED), while the other 35 patients underwent the channel discectomy (CD). The perioperative period, follow-up and imaging data of the two groups were compared. [Results] All the patients in both groups had operation performed successfully without serious complications. Although the ED group consumed significantly longer operative time than the CD group [(123.1±13.7)min vs (112.1±13.3), P=0.002], the for- mer proved significantly superior to the latter in terms of intraoperative blood loss [(15.6±3.1)ml vs (38.1±6.2)ml, P<0.001], total incision length [(1.1±0.3)cm vs (2.3±0.4)cm, P<0.001], postoperative walking time [(1.5±0.9)days vs (2.5±1.4)days, P<0.001] and hospital stay [(6.1± 1.4)days vs (8.4±1.7)days, P<0.001]. All of them were followed up for 12 to 36 months, with a mean of (24.08±5.17) months, the patients in the ED group resumed full weight-bearing activity significantly earlier than those in the CD group [(88.2±1.2)days vs (90.2±1.4)days, P< 0.001]. The VAS scores for lumbago and leg pain, as well as ODI scores significantly decreased over time in both groups (P<0.05). The VAS and ODI scores were not statistically significant between the two groups preoperatively (P>0.05). The ED group was significantly superior to the CD group in terms of VAS score for low back pain [(3.0±0.9) vs (3.3±1.0), P=0.028], VAS score for leg pain [(3.0±0.8) vs (3.5±0.9), P= 0.032] and ODI score [(20.7±4.0) vs (23.0±3.5), P=0.019] at discharge from hospital, whereas which became not statistically significant be- tween the two groups at the last follow-up (P>0.05). Imaging, intervertebral height and lumbar lordosis angle (L5S1 Cobb angle) were not sig-nificantly changed over time (P>0.05), however, the spinal canal area was significantly enlarged in both groups postoperatively compared with those preoperatively (P<0.05). There were no statistically significant differences in intervertebral height, spinal canal area and lumbar lordosis angle between the two groups at any time points accordingly (P>0.05). [Conclusion] Compared with the Quadrant channel counter- part, Delta endoscopic discectomy is less invasive and more beneficial to early recovery for giant L5S1 disc herniation in young adult.