Patients with epileptic seizures frequently complain of long-lasting cognitive impairment after a seizure. We evaluated this issue in 31 patients with epileptic seizures of a frontal (n = 8) or temporal lobe origin [right temporal lobe (RTL) n = 8/left temporal lobe (LTL) n = 15]. Seizures were secondarily generalized in 18 patients. Computerized testing of verbal and nonverbal recognition memory was performed before the seizure, directly after postictal reorientation, and 30 min and 1 h later. Repeated testing of 14 healthy persons served as control. The following results were obtained: Depending on seizure generalization, postictal reorientation times were 1-45 min. Frontal lobe seizures showed no effect on postictal memory performances, but verbal and visual recognition memory was significantly decreased after temporal lobe seizures. Decrease in either verbal or visual memory and time of recovery were related to lateralization of seizure onset. Functional recovery after reorientation lasted 30 min to 1 h. The decrease in performance was more severe after generalized seizures. Decision times during memory performance were not significantly affected by the seizures. Temporal lobe seizures lead to circumscribed and long-lasting memory deficits, which can be assumed to affect patients' capabilities seriously. Pre- and postictal testing is a useful tool for determining postictal cognitive impairment and in determining the site of seizure onset.