Electro-clinical correlations are reported in 200 elderly patients admitted to a psychiatric ward of a general hospital. Normal EEG characteristics were generally associated with functional psychiatric disorder. Abnormal EEG features correlated with organic brain syndromes (O.B.S.). The diagnostic and pathogenetic considerations and restrictions of EEG foci, intermittent rhythmic delta activity (Irda) and diffuse EEG slowing are discussed. The informative value of EEG dysfunction in geropsychiatry is emphasised.