Twenty-two patients with clinical symptoms suggesting lumbar spinal canal stenosis underwent myelography, computed tomography (CT), and magnetic resonance imaging (MRI). Patients were divided into two groups according to myelographic findings. Group I included 19 cases in which myelograms showed spinal canal stenosis, and group II consisted of 3 patients with myelograms negative for this condition. MRI showed uniform narrowing of the dural sac, indentations on the posterior aspect, or interruption of the outline of the sac in the sagittal scans and reduced area of the sac in the transverse scans. In group I patients, the diagnostic accuracy of MRI was greater than that of CT and myelography. In Group II patients, all of whom had moderate or severe lumbar scoliosis, MRI suggested spinal canal stenosis in contrast with myelography. In spinal canal stenosis surgery may be planned on the basis of MRI findings alone, except in scoliotic patients.