Forty-nine patients operated during an early clipping phase of cerebral aneurysm were reviewed; none had an associated ventricular flooding and/or intraparenchymal hematoma. Starting from the day of operation 37 patients were treated with anticonvulsant drugs using methods and dosages where were unlikely to guarantee efficacious cover. Forty-two patients made a satisfactory recovery, 5 patients died and 2 had severe neurological sequelae; 2 patients (4.4%) had early seizures during the first week after operation. In view of the inadequate cover of the anticonvulsant drugs and the homogeneous clinical characteristics of patients included in the study, the low number of attacks suggests an overall re-evaluation of anticonvulsant treatment and the need to select patients with a higher risk of an epileptic attack.