Electroconvulsive therapy (ECT) has antidepressive and antipsychotic effects. Since being introduced in Italy in 1938, its mode of action has still not been clarified. Treatment modalities have changed in many ways. ECT, in which a generalized epileptic seizure is provoked by electrical stimulation of the brain, is performed under short intravenous anesthesia and muscle relaxation. Considering careful previous clinical examination and anesthesiological and internal counterindications, ECT is a very safe form of treatment. Single cases of persisting memory impairment were described after the formerly common bilateral sinus wave stimulation. However, recent developments such as brief pulse stimulation, unilateral electrode placement, and individual stimulus titration (on the basis of EEG monitoring) make memory impairment as a consequence of ECT a rare event which mostly remits completely in 4-8 weeks. Today, ECT is performed mainly in patients suffering from severe, therapy-resistant affective or schizophrenic disorders. Pernicious catatonia and the neuroleptic malignant syndrome are emergency indications. Adequate ECT treatment requires a series of 6-12 individual sessions (every second or third day). In therapy-resistant depression, for which the greatest number of data are available, the response rate lies between 50 and 60%. This has been confirmed by a descriptive analysis of all ECT treatments at the Department of Psychiatry, University of Vienna, between 1994 and 2000. There is a need for controlled studies on continuation therapy subsequent to successful ECT.