Abstract:[Objective] To evaluate the primary clinical efficacy of unilateral biportal endoscopy (UBE) interbody fusion with double cages in the treatment of lumbar spondylolisthesis. [Methods] A retrospective study was conducted on 13 patients who underwent UBE interbody fusion with double lumbar interbody cages for lumbar spondylolisthesis from June 2021 to June 2023. The clinical and radiological data were evaluated. [Results] All patients underwent successful surgery with operation time of (152.6±33.4) min and intraoperative blood loss of (90.4±20.2) mL, without severe complications. The 13 patients were followed up for (13.3±1.4) months in a mean. The VAS for low back pain [point, (6.6±1.2), (2.7±0.8), (2.6±1.0), (2.5±1.1), P<0.001], VAS for leg pain [point, (6.9±1.7), (2.8±0.8), (2.6±1.1), (2.6±0.9), P<0.001], and ODI [%, (52.7±10.2), (29.3±10.4), (28.8±8.8), (27.5±7.3), P<0.001] significantly decreased over time preoperatively, 1 month postoperatively, 6 months postoperatively, and the last follow-up. Radiologically, compared with those preoperatively, the intervertebral space height [mm, (7.7±3.2), (11.5±2.6), P<0.001], the slippage ratio of the affected segment [%, (17.1±5.9), (11.0±3.0), P<0.001], and the lumbar lordosis angle [°, (27.5±14.2), (35.8±8.8), P<0.001] were significantly improved at the last follow-up. In addition, all the 13 patients achieved bony fusion of the affected intervertebral space, with no obvious cage displacement or subsidence, and no loosening or fracture of the pedicle screws at the last follow-up. [Conclusion] This UBE interbody fusion with double cages for the treatment of lumbar spondylolisthesis has significant clinical efficacy and high surgical safety. Therefore, it provides a new minimally invasive option for the treatment of lumbar spondylolisthesis.