The study objective is to assess the effectiveness of interlaminar decompression in patients with degenerative lumbar stenosis.Materials and methods. A prospective study was conducted among 100 patients with degenerative lumbar stenosis. All patients were operated, interlaminar decompression of the symptomatic side was made. Outcomes were assessed by using a visual analogue scale and Oswestry questionnaire 1 and 2 years after surgery. Among patients with an unsatisfactory result, the cause of the unsatisfactory outcome was studied.Results. One year after surgery a satisfactory result was noted in 71 patients, and 2 years after surgery a satisfactory result was noted in 67 patients. The following causes of unsatisfactory outcome were found in 33 patients: 9 – spinal canal restenosis, 2 – herniated disc at the operation level, 4 – the facet syndrome, 4 – development of clinical instability, 3 – pain in the opposite leg (there was no pain before the operation), 2 – development of delayed radiculopathy, 9 – decompensation of concomitant diseases (4 – coxarthrosis, 3 – gonarthrosis, 2 – chronic ischemia of the lower extremities). Among the risk factors for restenosis, statistically significant relationship was found only with the presence of spondylolisthesis.Conclusion. Interlaminar decompression is an effective surgical option in patients with degenerative lumbar stenosis. The presence of spondylolisthesis is a risk factor for the inefficiency of this operation.Conflict of interest. The authors declare no conflict of interest.Informed consent. All patients gave written informed consent to participate in the study