Seizure associated with antiemetics is rare. We report seizure associated with a 5-HT₃ receptor antagonist in a 38 years old female. The patient underwent ureterorenoscopic lithotripsy due to left upper ureter stone. After operation, the patient complained of nausea in the postanesthetic recovery unit. In order to subside symptom, the patient was administrated 5-HT₃ receptor antagonist, palonosetron, 0.075 mg intravenously. Shortly after administration of that, the patient developed generalized tonic-clonic seizures. The symptom was subsided after midazolam and thiopental sodium were injected. But 40 minutes later, seizure recurred and subsided with midazolam again. The patient recovered completely without any specific sequelae.