Considering the 87 cases without epilepsy or deterioration, we have found an abnormal or borderline EEG in 55% of this series of psychopathic personality. The type of abnomality is not specific, but has been seen in post-traumatic cases, adolescents and epileptics. The distribution and nature of the abnormalities is quite different from that found in a series of epileptics and there is no significant family history of epilepsy in these cases. The intellectual level and normal neurological findings of this group of patients is against birth trauma or organic cerebral disease.Parental history of psychopathic behaviour is consistent with either a hereditary predisposition or psychological stress, or both as causative factors.The early onset of these personality disorders is more consistent with hereditary or constitutional factors although it must be recognized that environmental factors may well produce this type of disorder at an early age where a relevant history is not available.Abstract Teaser