Several suspected etiologies can cause seizures during the resection of a brain tumor via a craniotomy: the tumor itself, intracranial hypertension or the anesthetic agents used, etc. Generalized myoclonic seizures, during general anesthesia in a 44 year old man, who underwent a resection for a relapsed frontal meningioma, were experienced. Anesthesia was induced and maintained using propofol and remifentanil. The myoclonic seizures began 30 minutes after the induction of anesthesia. The administration of rocuronium was unable to stop the involuntary movement. Midazolam was given to cease the seizures, but they continued for a further 105 minutes. After opening the dura mater, the seizures immediately disappeared and did not recur thereafter.