Abstract:[Objective] To compare the clinical efficacy and paraspinal muscles injury of unilateral biportal endoscopy (UBE) and open lumbar interlaminar fenestration decompression for the treatment of degenerative lumbar spinal stenosis (DLSS) . [Methods] A retrospec- tive study was done on a total of 68 patients who received surgical treatment for DLSS in our department from October 2019 to October 2020. Based on doctor-patient communication, 36 patients were treated with UBE, while the remaining 32 patients were treated with open lumbar interlaminar fenestration decompression. The perioperative, follow- up and imaging data were compared between the two groups. [Results] All patients in both groups had operations performed successfully without serious complications. The UBE group proved signifi- cantly superior to the open group in terms of incision length, postoperative walking and the hospital stay (P＜0.05) . In addition, the UBE group had significantly lower creatine kinase (CK) than the open group at 1 day postoperatively (P＜0.05) , whereas which became not statis- tically significant at 7 days postoperatively (P＞0.05) . The VAS and ODI scores decreased significantly (P＜0.05) , whereas the JOA score in- creased in both groups over time (P＜0.05) , which in the UBE group proved significantly superior to the open group at 7 days after opera- tion, and became not statistically significant between the two groups at 3 months after operation and latest follow-up (P＞0.05) . Radiographi- cally, although the UBE group had significantly less spinal canal area than the open group (P＜0.05) , the former had significantly greater paravertebral muscle cross-sectional area, whereas associated with significantly less paravertebral muscle atrophy than the latter at the lat- est follow up (P＜0.05) . [Conclusion] The UBE has the advantages of quite less trauma to paravertebral muscles, while faster postoperative recovery for treatment of DLSS, and achieves the similar clinical outcome as open surgery.