Purpose <p>Unilateral biportal endoscopic (UBE) lumbar discectomy is an effective minimally invasive technique for lumbar disc herniation (LDH). However, no study has compared the outcomes between ipsilateral and contralateral inclinatory approaches. This study evaluated these approaches and described strategies to reduce recurrence.</p> Methods <p>Data from 93 patients who underwent UBE lumbar discectomy at a single institution were retrospectively reviewed (ipsilateral: 70 levels, contralateral inclinatory: 39 levels). Clinical outcomes included back and leg visual analog scale (VAS) scores and Oswestry Disability Index (ODI). Radiological outcomes were assessed using lumbar lordosis, segmental angle, disc height on X-ray and facet length, superior articular process (SAP) cross-sectional area, surgical approach angle on computed tomography (CT). Correlations between surgical approach angle and facet resection rates were analyzed.</p> Results <p>Both approaches showed significant improvement in back and leg VAS scores and ODI and had no significant differences between segmental angle and disc height changes. Lumbar lordosis increased significantly in both groups. Facet length resection rate was 9.73% and 11.07% in the ipsilateral and contralateral inclinatory groups, respectively. Large surgical approach angle correlated with increased SAP cross-sectional area resection but not with facet joint resection.</p> Conclusions <p>Ipsilateral and contralateral inclinatory UBE lumbar discectomy yielded comparable clinical and radiological outcomes. Approach choice can be based on surgeon’s preference and patient’s anatomy. To minimize the risk of recurrence, we highlight the importance of adequate foraminotomy and removal of loose fragments within bulging annulus.</p>