To evaluate the width of the spinal canal when diagnosing spinal stenosis, 91 patients older than 59 years of age when undergoing myelography were studied. Using a sagittal diameter of 11 mm as border for the diagnosis of spinal stenosis, it was found that 31 of the 66 patients with spinal claudication, suspicion of spinal claudication and sciatic pain fulfilled this criterion and that 3/25 of the control group and those with atypic symptoms had a sagittal diameter of 11 mm or less. Five patients showed a complete block on the myelogram, and all of them had a typical spinal claudication. The spinal canal will narrow with age in asymptomatic patients as well, and the myelographic stenosis in elderly patients is not always equivalent to a clinical diagnosis of spinal stenosis.