Spinal arachnoiditis is a rare condition, The arachnoiditis of various causes leptomeningeal meastasis lep-tomeningeal lymphoma hypertrophic polyneuritis etc. are known to have a similar radiologic manifestations. The authors reviewed myeolographic findings of 20 patients with spinal arachnoiditis retrospectively to discovery any specific findings helpful to make a differential diagnosis. The causes of spinal arachnoiditis were tuberculous origin in 9 cases pyogenic in 2 postoperative in one lymphoma in 3 and leptomeningeal metastasis in 5 Myelographic findings of tuberculous spinal arachnoiditis were block of CSF(89%) especially at the conus medullaris level multiple fine and/or coarse nodular filling defects (78%) nerve root thickening(56%) focal ir-regular adhesive filling defects(44%) and irregular or indistinct thecal sac margin(44%) Irregular adhesive band-like filling defects and/or multiple fine nodular filling defects seem to be characteristics of the arachnoiditis. Myelographic findings showing coarse nodular filling defects without fine ones are suggestive of leptomeningeal metastasis.