Aim:Lumbar spinal stenosis (LSS) can have an unfavorable impact on activities of daily living and walking distance. Bilateral decompression via unilateral approach (BDUA) could be an effective method of reducing pain, increasing walking distance, and improving disability, although some reports have shown that it could have poor outcomes in the long-term, particularly in older people and females. This study was conducted to investigate the mid-term efficacy of BDUA on symptoms and quality of life of patients, especially in elderly and/ or female patients with low grade (with percent slip <25%) degenerative spondylolisthesis or without spondylolisthesis.Material and Methods:The study included patients who underwent BDUA due to one or two-level LSS related to degenerative spondylosis and/ or degenerative spondylolisthesis. Pre- and postoperative data of the Oswestry Disability Index (ODI), Visual Analogue Scale (VAS), and walking distance were compared.Results:Evaluation was made of a total of 53 patients, comprising 32 males and 21 females with a mean age of 60.6±9.0 years. Compared with preoperative data of VAS, ODI and walking distance improved significantly in all patients at the 3-year follow-up examination. Furthermore, a significant improvement was determined in the clinical parameters of patients with degenerative spondylolisthesis, with no worsening of slip and no requirement for instrumentation. Moreover, when patients were separated into two groups according to age, as elderly (>60 years) and adult (<60 years), similar improvements were seen in both groups.Conclusion:BDUA could be quite effective in reducing pain, improving walking distance with no worsening of the grade or degree of slipping, and improving quality of life.