The study was conducted to compare the side effects in myelography of the two non-ionic water-soluble contrastmedias, Iopamidol(Niopam) and Metrizamide(Amipaque). A total of 111 patients were examined, 64 with Iopamidol and47 with Metizamide. Side effects consisted of headache, nausea, vomiting, dizziness, urinary difficulty, muscularpain, seizure, neurobehavioral distrubance, neurologial sign change, vital sign change and etc. The common sideeffects were headache, nausea, vomiting and dizziness in order of frequency. Most of the side effcts were subsidedwithin 24 hours following meylography. Iopamidol myelography caused fewer and milder side effects than Metrizamidestudy. The side effects were more commonly observed in cervial, thoracic or total myelography than in lumbarmyelography with either lopamidol or Metrizamide. There was no significant correlation between incidence of theside effects and premedication with phenobarbital or valium injection before myelography and CSF sampling duringthe procedure.