A prolonged video/electroencephalogram (EEG) monitoring was performed in two patients with intractable epilepsy after adult onset acute encephalitis. Clinically both patients were thought to have a localized epileptogenic focus because of the single stereotyped clinical seizures by history in two patients, and a well localized lesion shown by MRI in one patient. The video/EEG monitoring, however, revealed multiple EEG foci ictally as well as interictally in both patients. Moreover, both patients were found to have at least two different patterns of clinical seizures. In patients with adult onset postencephalitic epilepsy, therefore, it is necessary and important to evaluate enough number of seizures by prolonged video/EEG monitoring even if seizures are clinically stereotyped by history and localized lesions are present on brain imaging.