Abstract:[Objective] To investigate the clincal outcomes of unilateral biportal endoscopy (UBE) for lumbar spinal stenosis (LSS) with nocturnal pain (NP) as the main clinical manifestations. [Methods] A retrospective study was performed on 16 patients who received UBE for LSS with NP as the main manifestation in our hospital from September 2020 to December 2021. The clinical and imaging documents were evaluated. [Results] All the 16 patients had the UBE procedures performed successfully without serious complications, while with op- eration time of (68.2±7.6) min, total incision length of (2.5±0.5) cm, postoperative walking time of (2.3±0.5) days, and hospital stay of (6.8± 0.9) days. All of them were followed up for an average of (10.3±2.2) months. With time elapsed preoperatively, at dischange and the latest follow-up, theVAS score [(5.8±0.4), (3.6±0.5), (1.1±0.7), P<0.05] and the ODI sleep score [(3.4±0.5), (2.4±0.5), (0.3±0.6), P<0.05] signifi- cantly decreased. Radiographically, vertebral canal sagittal diameter [(9.9±0.5) mm, (17.6±1.2) mm, (17.4±1.2) mm, P<0.05] and vertebral canal area [(0.9±0.1) cm2 , (1.5±0.1) cm2 , (1.5±0.1) cm2 , P<0.05] significantly increased. At the last follow-up, the consequence was marked as excellent in 13 cases, good in 2 cases and fair in 1 case with excellent and good rate of 93.8% according to the modified MacNab criteria. [Conclusion] This UBE does effectively relieve pain symptoms and improve sleep status for patients who have LSS with NP as the main manifestation.