Prediction of seizure control after surgery on cerebral arteriovenous malformations (AVM's) is currently unavailable. Between 1982 and 1990, 54 patients (30 males, 24 females) with epilepsy caused by a supratentorial cerebral AVM, without prior manifestation of intracranial hemorrhage, were surgically treated. Patients ranged in age from 11 to 59 years at seizure onset and from 13 to 70 years at surgery; the duration of seizure history ranged from several months to 27 years. The AVM's were located in the temporal (17 cases), frontal (15), parietal (10), rolandic (two), and occipital (two) regions; eight were multilobular. All patients underwent preoperative electroencephalography, intraoperative electrocorticography, and total excision of the AVM; additional cortical excision was performed in 25 cases. Remote seizure foci were identified in the ipsilateral mesial temporal structure in 10 patients with AVM's located in the lateral or posterior temporal lobe and in one with an AVM in the anterior frontal region. Two patients required a second operation to remove a remote seizure focus. Among the 54 patients, there were no operative deaths. After surgical treatment, two patients developed hemiparesis, one had contralateral paresthesia of limbs, two suffered partial visual field defects, and five experienced temporary speech disturbances. Postoperative results of seizure control during follow-up study (mean duration 4.8 years) were excellent in 38 patients (70.4%), good in 10 (18.5%), fair in five (9.3%), and poor in one (1.9%). Results appear to correlate with age at seizure onset, duration of seizures, location of lesions, and cortical excision. Excellent results were shown in 18 (60%) of 30 patients whose age at seizure onset was 30 years or less and in 20 (83.3%) of 24 whose age at seizure onset was greater than 30 years. Eighteen (90%) of 20 patients had excellent results when seizure duration was 1 year or less; only 25% of these underwent cortical excision. Twelve (71%) of the 17 temporal AVM's were associated with demonstrable epileptic foci. Secondary epileptogenesis can occur in humans with supratentorial cerebral AVM's; cortical excision in selected patients can improve the outcome of seizure control. Early surgery of a cerebral AVM in young patients presenting with epilepsy is an important consideration.