1. Nine patients, 4 with depression, 5 with schizophrenia, were studied with respect to changes in the beta activity of the EEG induced by the intravenous injection of sodium amytal mg. 250 (with racemic amphetamine sulfate mg. 20). These changes were measured on 5 consecutive days prior to a course of electric convulsive therapy. They were again studied in a single session, after this course of treatment.2. There was observed to be a striking increase in beta activity after the injection. This increase was greatest in the frontal EEG, least in the occipital EEG, forming an anterior-posterior per cent time gradient, which was an accentuation of the preinjection gradient.3. There was no systematic electrocortical tolerance developed in either group, to the drug, over a 5-day period. The schizophrenic group, however, developed the usual psychological tolerance.4. After a course of electric convulsive therapy there was a decrease in percent time beta; the response of beta to sodium amytal was greatly reduced, particularly in the fronral area.5. These data suggest that the electrocortical response measured (per cent time beta) and the psychologic state are reflections of the activity of different neural systems.