Lumbar spinal stenosis (LSS) is a relatively common condition of varied aetiology which results in chronic compression of the cauda equina. It becomes clinically relevant when giving rise to symptoms of neurogenic claudication or leg pain. Lumbar spinal stenosis can be classified based on anatomy or aetiology and the diagnosis in any single case should include a consideration of both the site and the cause. Plain radiography is of limited value. Myelography with erect lateral flexion/extension views will demonstrate the dynamic component of the stenosis which cannot be appreciated on plain computed tomography (CT) or magnetic resonance imaging (MRI). Therefore, in patients with a good history of symptomatic LSS, and a borderline stenosis on MRI, CT myelography is recommended as the definitive pre-operative imaging investigation.