Prolonged video-EEG-monitoring facilitates a correlation of clinical seizure semiology and corresponding EEG changes. Indications for prolonged video-EEG-monitoring comprise differential diagnosis of epileptic and psychogenic seizures, correct classification of epileptic syndromes and presurgical evaluation of patients with medically refractory focal epilepsies. 6000 patients in Austria would benefit from epilepsy surgery with an additional 150 bis 200 new patients appearing each year. Presurgical evaluation consists of a non-invasive Phase I and an invasive Phase II. During Phase I each patient is evaluated with a prolonged video-EEG-monitoring with scalp-EEG, a MRI-scan, a SPECT- and/or PET-scan, a neuropsychological evaluation and a Wada-test. If the epileptogenic zone cannot be localized adequately with these methods, invasive electrophysiological techniques with intracranial (epidural peg-electrodes, foramen-ovale electrodes, subdural strip or grid electrodes) or intracerebral electrodes (stereotaxically implanted depth electrodes) have to be applied. Epilepsy surgery renders 70 to 80% of patients seizure free and thus can regarded an effective and safe treatment option for patients with medically refractory focal epilepsies.