Abstract:[Objective] To compare the clinical efficacy of percutaneous endoscopic transforaminal discectomy (PETD) versus percuta- neous endoscopic interlaminar discectomy (PEID) for severely prolapsed lumbar disc herniation. [Methods] A total of 60 patients who admit- ted to our hospital from January 2018 to January 2019 for severely migrated lumbar disc prolapse were randomly divided into two groups. Among them, 30 patients were undergoing PETD, while the other 30 patients were undergoing PEID. The perioperative, follow-up and imag- ing data of the two groups were compared. [Results] In the PETD group, 3 patients were withdrawn from this study due to unable complete of the operation on plan, therefore a total of 57 patients were included in the study finally. Although there were no significant differences between the two groups in terms of incision length, volume of nucleus pulposus resected, ambulation time, early complications and hospital stay be- tween the two groups (P＜0.05) , the PEID group proved significantly superior to the PETD group in terms of operation time, intraoperative blood loss and fluoroscopy times (P＜0.05) . The VAS scores for low back pain and leg pain, as well as ODI scores decreased significantly (P＜ 0.05) , whereas JOA scores increased significantly in both groups over time (P＜0.05) . However, there was no statistically significant differ- ence between the two groups in aforesaid scores at any matching time points (P＞0.05) . Radiographically, the height of the intervertebral space significantly declined (P＜0.05) , while lumbar lordosis angle remained unchanged significantly (P＞0.05) in both groups at the latest follow up compared with those preoperatively. There were no significant differences in intervertebral height and lumbar lordosis angle between the two groups at any corresponding time points (P＞0.05) . [Conclusion] Both PETD and PEID are effective for treatment of severely prolapsed lum- bar disc herniation, by comparison, the PEID takes more advantages.