Abstract:[Objective] To compare the clinical outcomes of unilateral biportal endoscopy (UBE) versus traditional transforaminal lum- bar interbody fusion (TLIF) for lumbar spine stenosis (LSS). [Methods] A retrospective study were done on 45 patients who received surgical treatment for LSS from November 2019 to July 2021. According to doctor-patient communication, 20 patients received UBE, while the other 25 patients received TLIF. The perioperative period, follow-up and imaging documents were compared between the two groups. [Results] Al- though there were no significant differences in operation time and incision healing grade between the two groups (P>0.05), the UBE group proved significantly superior to the TLIF group in terms of total incision length [(2.2±2.2)cm vs (10.2±1.7)cm, P<0.05], intraoperative blood loss [(35.0±21.3)ml vs (472.0±171.4)ml, P<0.05], intraoperative fluoroscopy times [(6.1±0.9)times vs (10.0 ±2.3)times, P<0.05], the postoper- ative ambulation time [(1.5±0.7)days vs (3.7±1.0)days, P<0.05] and hospital stay [(13.4±3.2)days vs (17.8±7.2)days, P<0.05]. All patients in both groups were followed up for more than 12 months, and the UBE group resumed full weight-bearing activities significantly earlier than the TLIF group [(70.3±11.9)days vs (90.4±13.4)days, P<0.05]. The VAS scores for back pain and leg pain, as well as ODI and JOA scores sig- nificantly improved in both groups with time (P<0.05). The UBE group was significantly better than the TLIF group in terms of VAS score for low back pain [(2.5±0.5) vs (4.2±0.9), P<0.05], ODI score [(11.2±5.0) vs (18.8±9.0), P<0.05], JOA score [(20.9±3.5) vs (17.5±2.8), P<0.05] a month postoperatively. However, there were no significant differences in the above indexes between the two groups at the last follow-up (P> 0.05). Regarding imaging, the spinal canal area increased significantly in both groups postoperatively compared with those preoperatively (P<0.05), which in UBE group was significantly smaller than that in TLIF group after operation [(191.6±33.8)cm2 vs (244.6±21.9)cm2 , P<0.05]. Moreover, there were no significant changes in intervertebral height and lumbar lordosis angle in both groups before and after surgery (P> 0.05), and there were no statistically significant differences between the two groups in intervertebral space height and lumbar lordosis angle at any time points accordingly (P>0.05). [Conclusion] Both UBE and TLIF do achieve good clinical outcomes in the treatment of LSS. By comparison, the UBE takes advantages of less trauma, faster recovery and less early postoperative lumbago over the TLIF, which is especially suitable for LSS with fewer segments involved.