1. In a series of 58 patients receiving shock therapy the character of the preshock EEG record was found to be directly related to age and to severity of clinical disorder.2. There was an unusually high incidence of abnormal records in this series.3. The degree of change in EEG which resulted from shock therapy was related to the type of preshock record. Those records which were abnormal, fast or paroxysmal preceding shock were those which changed most during shock therapy.4. It is therefore probable that the preshock record is of diagnostic and prognostic importance as related to treatment of psychotic patients by electric shock.Abstract Teaser