Electroencephalographic (EEG) video monitoring is the simultaneous documentation of the clinical and electroencephalographic manifestations of seizures. The video recording permits repeated viewing of the clinical sequence and enables comparisons with recordings of known seizures. Epilepsy is a clinical diagnosis in which most cases can be characterized with the standard clinical history, examination, and EEG. Studies of the treatment of intractable seizures (unsatisfactory control of seizure) indicate that more complex cases may require the data obtained with EEG video monitoring. For patients with intractable seizures, EEG video monitoring may help to confirm or support a diagnosis of epilepsy or confirm or support a differential diagnosis of physiologic or psychogenic seizures (nonepileptic attacks) from epilepsy. Monitoring also may provide a more accurate classification of the epileptic seizures and, for patients evaluated for surgical treatment, establish clinical focality. Estimates of the percentage of epilepsy patients requiring EEG video monitoring range from 5 to 30 percent. The average length of monitoring is approximately 10 to 16 days. In some cases outpatient monitoring in conjunction with activation procedures provides patient evaluation in only 6 to 8 hours.