PURPOSE: We performed this study to describe the findings of MR Myelography(MRM) of herniated disc disease, spinal stenosis and spinal tumor and to evaluate the usefulness of the MRM in comparison to MRI. MATERIALS AND METHODS: MRI and MRM were performed in 31 patients with herniated disc disease(12 patients), spinal stenosis(11 patients) and spinal tumor(8 patients). MRI and MRM were done with 1.5-T Signa MR, using fat suppressed heavily T2-weighted fast spin echo technique. We retrospectively analyzed MRM images about the thecal sac indentation, compression or displacement of the nerve root, extent and degree of narrowing of spinal canal, relationship between spinal tumor and spinal cord. MRM findings were compared with MRI in all cases. RESULTS: In 18 herniated disc cases of 12 patients, focal filling defect with cutoff or displacement of the nerve root in eight cases of paracentral herniated disc was seen. Cutoff and displacement of the nerve root were more clearly delineated on MRM than rvlRI. In the patients of spinal stenosis(11 cases), hourglass deformity of the thecal sac or complete spinal block of the subarachnoid space was clearly demonstrated. The extent and severity of spinal stenosis were more accurately evaluated on MRM than MRI. MRM finding of intramedullary tumor(3 cases) was enlargement of spinal cord. Five cases of intradural extramedullary tumor showed intradural filling defect, which caused contralateral displacement of the spinal cord with meniscus sign on inferior margin of the mass. CONCLUSION: MRM shows characteristic findings of herniated disc disease, spinal stenosis and spinal tumor. MRM yields excellent definition of the thecal sac, nerve roots and nerve root sleeves in relation to herniated disc and may be more accurate in evaluation of the degree and extent of spinal stenosis than MRI.