PURPOSE: Lumbar disc herniation is a prevalent condition that leads to lower back pain, weakness, and claudication. While microdiscectomy has long been the gold standard for surgical treatment, advances in technology have introduced endoscopic techniques, such as Unilateral Biportal Endoscopic spine surgery. Despite these advances, epidural fibrosis remains a common complication that, potentially hinders recovery and complicating revision surgeries. This study aimed to compare the extent of epidural fibrosis between microdiscectomy and UBE surgery with preserved flavum and flavectomy. METHODS: This retrospective study included 47 patients diagnosed with lumbar disc herniation who underwent surgery between August 2020 and July 2022 at two tertiary university hospitals. The patients underwent endoscopic surgery with flavum preservation (n = 16), flavum excision (n = 16), lumbar microdiscectomy with flavectomy (n = 15). Preoperative and postoperative imaging, including X-rays, computed tomography, and magnetic resonance imaging were performed. Functional scores (Visual Analog Scale, Japanese Orthopedic Association score, and Oswestry Disability Index were assessed. Postoperative magnetic resonance imaging was conducted at three months to evaluate epidural fibrosis. RESULTS: The rate of epidural fibrosis was significantly lower in the flavum sparing UBE (0.18 ± 0.17) compared to the flavum non-sparring UBE (0.38 ± 0.19) and the flavum non-sparring microdiscectomy (0.47 ± 0.18) (p < 0.001). Functional scores significantly improved postoperatively in all groups, with significant differences noted in JOA, Oswestry, and VAS scores (p < 0.01). Early functional score differences between the groups were found to be significant in favor of UBE, particularly in the flavum-sparing group. CONCLUSION: The preservation of flavum during UBE surgery leads to significantly less epidural fibrosis compared to both flavum non-sparring UBE and microdiscectomy. Functional improvements were similar across groups, but flavum sparring UBE surgery demonstrated better early postoperative outcomes. The results suggest that preserving flavum during endoscopic spine surgery may reduce epidural fibrosis formation and promote better recovery, supporting the benefits of minimally invasive techniques in lumbar disc herniation surgery.