Objective : Lumbar spine stenosis (LSS) can result in symptomatic compression of the neural elements, requiring surgical treatment if conservative management fails. Minimally invasive surgery has come to be more commonly used for the treatment of LSS. The current study describes outcomes of bilateral microdecompression by unilateral or bilateral laminotomy (BML) for degenerative LSS after a minimum follow-up period of 3 years and investigates factors that result in a poor outcome. Methods : Twenty-one patients who were followed-up for at least 3 years were included in this study. For clinical evaluation, the Japanese Orthopedic Association (JOA) scoring system for low back pain was used. The modified grading system of Finneson and Cooper was used for outcome assessment. Radiographic evaluation was also performed for spondylolisthesis, sagittal rotation angle, and disc height. Results : Twenty-one patients (10 men, 11 women) aged 53-82 years ($64.1{pm}8.9$ years) were followed-up for a minimum of 3 years (36-69 months). During follow-up, two patients underwent reoperation. Average preoperative JOA score and clinical symptoms, except persistent low back pain, improved significantly at the latest follow-up. There were no significant differences in radiological findings preoperatively and postoperatively. Thirteen patients (61.9%) had excellent to fair outcomes. Conclusion : BML resulted in a favorable and persistent outcome for patients with degenerative LSS without radiological instability over a mid-term follow-up period. Persistent low back pain unrelated to postoperative instability adversely affects mid-term outcomes.