This study was intended to investigate the pre-and postoperative profile of seizures in the patients with cerebral arteriovenous malformatins(AVM's), and to evaluate various preoperative factors to predict the postoperative occurrence of seizures. The patients consisted of 46 consecutive cases with supratentorial AVM's operated on from May 1987 to May 1993. Their mean follow-up duration was 40 months. The pre- and postoperative seizure profiles were similar to each other. The overall incidence of patients experiencing seizure were 50% preoperatively and 52% postoperatively, and the incidence of intractable seizure was 15%, which was the same in both the pre-and postoperatively period. The presence of preoperative seizure and large size of AVM were significant indicators of high incidence of postoperative seizures(P<0.05), while other factors such as preoperative intracerebral hemorrhage or embolization showed no significant influence on the occurrence of postoperative seizures. About 70% of the patients with preoperative seizures also had postoperative seizures, while those without preoperative seizures developed new ones only in 35% of the cases postoperatively. The mean size of the AVM's in the group, with postoperative seizures was larger than that of the group without postoperative seizures(4.56 vs. 3.02 cm). Regarding postoperative intractable seizures, 57% of the group with preoperative intractable seizures remained intractable postoperatively and groups with preoperatively controlled and groups without seizures demonstrated postoperative intractablity only in 13% and 4% respectively. In conclusion, surgery of AVM's did not change the overall incidence of seizures, both controlled and intractable, and patients with preoperative and large sized AVM's and significantly higher possibility of postoperative seizures. Patients with preoperative intractable seizures resulted in control of seizures in 43% after removal of AVM, while 57% remained intractable. Extirpation of epileptic focl, after localization with preoperative study, seems to be needed to improve the outcome of the postoperative seizures.