The study was conducted to compare the side effects in myelography of the two non-ionic water-soluble contrast medias, lopamidol(Niopamⓡ) and Metrizamide(Amipaqueⓡ). A total of 111 patients were examined. 64 with lopamidol and 47 with Metrizamide. Side effects consisted of headache, nausea, vomiting , dizziness, urinalry diffculty, muscular pain, seizure, neurobehavioral disturbance neurological sign change, vital sign change and etc, The common side effects were headache, nausea, vomiting and dizziness in order of frequency. Most of the side effects were subside within 24 hours following myelography. lopamidol myelography caused fewer and milder side effects than Metrizamide study. The side effects were more commonly observed in cervical, thoracic or total myelography than in lumbar myelography with either lopamidel or Metrizamide. There was no significant correlation between incidence of the side effects and premedication with phenobarbital or valium injection before myel graphy and CSF sampling during the procedure.