Spinal arachnoiditis is a rare condition. The arachonoiditis of various causes, leptomeningeal meastasis, leptomeningeal lymphoma, hypertropic polyneuritis, etc. are known to have a similar radiologic manifestations. The authors reviewed myelographic findings of 20 patients with spinal arachomiditis retrospectively to discovery anyspecific 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 metastatisis in 5. Myelographic findings of tumberculous spinal arachnoiditis were block of CSF(89%), especially at the conusmedullaris level, multiple find and/or coarse nodular filling defects (78%), nerve root thickening (56%), focalirregular adhesive filling defects (44%) and irregular or indistinct thecal sac margin(44%). Irregular adhesiveb and-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.