We encountered a patient who had a rare occurrence of a seizure after lumbar myelography from the beginning of this untoward side effect. Clinical trials with iohexol in myelography have demonstrated a good tolerability of this water-soluble contrast medium. However, there have been a few reports that have shown acute adverse reactions such as headaches, vomiting, psychosis, confusion and generalized tonic-clonic seizures. Despite the reports on the safety of iohexol use, it may cause a generalized seizure attack without an epileptogenic history. Therefore, thorough attention and the preparation for emergency treatments for the seizure are essential in every myelography using iohexol as a contrast medium. Moreover, in order to avoid unwanted legal problems, the patients and their family need to be informed of the necessity and possible side effects associated with myelography.