Degenerative spondylolisthesis is a unique form of spondylolisthesis that is characterized in most patients as a hypertrophic arthritis of the facet joint resulting in segmental instability predominantly in the sagittal plane. Disk degeneration is associated with degenerative spondylolisthesis to a varying degree. Joint involvement may not be uniform in all patients, and a rotary component, although small, is often present. The fourth to fifth lumbar level is most often involved, particularly in association with a relatively rigid lumbosacral segment. Degenerative spondylolisthesis is more common in females and in blacks, and it seldom occurs before the age of 40 years. Symptoms are generally due to lateral stenosis that compromises the inferior nerve roots, usually at the level of the fifth lumbar vertebra. However, the superior nerve roots can be compressed in more advanced cases. Neurogenic claudication and radiculopathy are commonly reported symptoms at the time a patient is first examined. The findings of physical examination vary; less than half of the patients examined exhibit a neurologic deficit. Rarely, a patient has cauda equina syndrome at the time of initial examination. Mild cases can be successfully treated surgically, but significant neurologic symptoms can only be diminished by adequate decompression. We recommend posterolateral fusion because of the deformity's propensity to progress postoperatively.