Cross-sectional studies of the lumbar spinal canal were performed by computerised tomography in asymptomatic subjects and in patients with myelographic and clinical findings suggestive of lumbar stenosis. In most cases stenosis was found to be developmental or combined in nature. Computerised tomography is a useful adjunct to myelography in the evaluation of lumbar stenosis as it enables an accurate assessment to be made of the type, degree and extent of narrowing of the vertebral canal.