Delirium, also known as acute confusional state, is a common reversible organic psychiatric syndrome. This paper focuses on toxic delirium associated with prominent paroxysmal electroencephalogram (EEG) dysfunction occurring in nonepileptic patients. Our data derive from observations in two conditions, viz., delirium induced by hypnosedative drug withdrawal and confusion activated by psychotropic drug overdosage. It is suggested that in these conditions, delirium represents a generalized symptomatic nonconvulsive epileptic state following a transient transmitter dysfunction. Dramatic relief of both clinical and EEG dysfunction by intravenous benzodiazepines is reported in detail. Finally, the informative value of the EEG in the differential diagnosis of acute confusional states is emphasized.