A previously healthy 15-year-old boy initially diagnosed to have acute psychotic reaction had a history of a single generalized seizure and prolonged amnestic states of varying intensity and duration. An ictal electroencephalogram (EEG) showed bitemporal ictal discharges starting from the left side. Carbamazepine was started. A magnetic resonance imaging (MRI) obtained on the 10(th) day of the antiepileptic therapy showed increased signal intensity on the T2 weighted images. The patient's memory function markedly improved during 10 months' follow-up with antiepileptic treatment, although he described brief attacks of dizziness. A repeat MRI examination showed normal findings. The amnestic states were thought to be due to frequent complex partial seizures, and transient MRI changes to hippocampal edema. This case illustrates the importance of epileptic disorders in the differential diagnosis of psychiatric conditions.