Objective: Although prophylactic antiepileptic drug (AED) use in patients with aneurysmal subarachnoid hemorrhage (SAH) is a common practice, lack of uniform definitions and guidelines for seizures and AEDs rendered this prescription more habitual instead of evidence-based manner. We herein evaluated the incidence and predictive factors of seizure and complications about AED use. Methods: From July 1999 to June 2007, data of a total of 547 patients with aneurysmal SAH who underwent operative treatments were reviewed. For these, the incidence and risk factors of seizures and epilepsy were assessed, in addition to complications of AEDs. Results: Eighty-three patients (15.2%) had at least one seizure following SAH. Forty-three patients (79%) had onset seizures, 34 (6.2%) had perioperative seizures, and 17 (3.1%) had late epilepsy. Younger age (< 40 years), poor clinical grade, thick hemorrhage, acute hydrocephalus, and rebleeding were related to the occurrence of onset seizures. Cortical infarction and thick hemorrhage were independent risk factors for the occurrence of late epilepsy. Onset seizures were not predictive of late epilepsy. Moreover, adverse drug effects were identified in 128 patients (23.4%) with AEDs. Conclusion: Perioperative seizures are not significant predictors for late epilepsy. Instead, initial amount of SAH and surgery-induced cortical damage should be seriously considered as risk factors for late epilepsy. Because AEDs can not prevent early postoperative seizures (< 1 week) and potentially cause unexpected side effects, long-term use should be readjusted in high-risk patients.