Degenerative spinal stenosis of the lumbar spine is caused by many factors, some of which include: disc herniation, ligamentum flavum and facet hypertrophy, spondylolisthesis, and compression fracture. Most often the stenosis is caused by a combination of these factors. The imaging modalities in routine use to evaluate these conditions are computed tomography, magnetic resonance imaging and computed tomography-myelogram. They each have their advantages and disadvantages although any one of these modalities can adequately diagnose lumbar stenosis. The overall accuracy rate of computed tomography, magnetic resonance imaging, and computed tomography-myelogram has been reported to be similar and even complimentary. It is recommended that the least invasive modality be performed first. Magnetic resonance imaging should be the first choice because it does not require ionizing radiation or contrast injection. The aim of the current study is to present the common causes of lumbar stenosis. Where appropriate, each case is shown with images from each modality so that their similarities and differences can be highlighted.