Abstract Background: Adjacent segment degeneration (ASD) is one of the most communal drawbacks of lumbar fixation. Adjacent segment disease means degeneration developing at mobile segments above or below fixed spinal level. The lowest cranial mobile segment is the mostcommunal level for the development of adjacent instability. Laminectomydisturbs the integrity of the posterior spinal complex. Aim of Study: The main aim of this study was to detect the incidence of adjacent segment degeneration following laminectomy and the incidence of degeneration without laminectomy in levels adjacent to those operated upon by lumbar posterolateral fixation via a comparative study and results of 1 year clinical follow-up. Patients and Methods: A retrospective review was con-ducted on 40 patients who underwent lumbar posterolateral fixation in one institute from June 2021 to January 2022. 20 patients operated upon by laminectomy and fixation of the same levels without any adjacent segment laminectomy. The other 20 patients operated upon by laminectomy and fixation of the same levels with additional laminectomy of a cranially adjacent level. Results: 40 patients underwent lumbar posterolateral fixation. Of those, 20 patients operated upon by laminectomy and fixation of the same levels without any adjacent segment laminectomy, 2 patients only developed ASD. In the other 20 patients operated upon by laminectomy and fixation of the same levels with additional laminectomy of a cranially adjacent level, 12 patients developed ASD either radiologically or clinically. Conclusions: ASD should be well-thought-outto be a long-term drawback of lumbar or lumbosacral fusion. Many studies proved that the fusion enforcesremarkable degree of stress at the adjacent segment. ASD occurs often with additional decompression above the level of posterolateral fixation within lumbar spine surgery. A surgery that maintains as much of the posterior element as possible should be considered to guard against future degeneration in cases of which the adjacent segments need decompression in the form of laminectomy.