THE RELATION OF VIOLENCE TO BRAIN FUNCTION IN HUMANS HAS BEEN THE SUBJECT OF MANY STUDIES. A RECENT EXPERIMENT SHOWED A HIGHER DEGREE OF EEG ABNORMALITY IN HABITUALLY VIOLENT CRIMINALS THAN IN CRIMINALS INVOLVED IN A SINGLE VIOLENT EVENT. USING THIS APPROACH, THE INVESTIGATION COMPARED THE FOLLOWING GROUPS OF PATIENTS IN A PSYCHIATRIC HOSPITAL: SEVEN NONPSYCHOTIC PERSONS WHO HAD BEEN REPETITIVELY INVOLVED IN ASSAULTIVE INCIDENTS, EIGHT NONPSYCHOTIC PATIENTS WITH ANTISOCIAL BEHAVIOR BUT NO REPEATED ASSAULTS, AND SIX INDIVIDUALS WITH KNOWN BRAIN DAMAGE WHO WERE INCLUDED FOR COMPARISON PURPOSES. EACH SUBJECT WAS GIVEN AN EEG EXAMINATION AND A SERIES OF TESTS TO DETECT IMPAIRMENT IN THE MOTOR, SENSORY, MEMORY, AND COGNITIVE ASPECTS OF BRAIN FUNCTIONING. THE RESULTS OF THE TESTS WERE IDENTICAL FOR THE BRAIN-DAMAGED GROUP AND THE PERSONS WITH REPETITIVE ASSAULTIVE BEHAVIOR. THE DATA FOR THESE TWO GROUPS DIFFERED CONSIDERABLY FROM THE NONAGGRESSIVE BEHAVIOR DISORDER PATIENTS IN THAT THE LATTER EXHIBITED A MORE NORMAL OR BETTER PERFORMANCE. THE SIGNIFICANT VARIABLES WERE EEG ABNORMALITY, DEGREE OF ESTABLISHMENT OF HAND DOMINANCE, PERSEVERATION ERRORS IN A VISUOMOTOR TASK, AND VERBAL SHORT MEMORY. PAROXYSMAL ACTIVITY, PARTICULARLY IN THE FRONTAL AREA, APPEARED TO BE THE MOST IMPORTANT EEG CHARACTERISTIC RELATED TO VIOLENT BEHAVIOR. THE PREVALENCE OF AMBIDEXTROUS INDIVIDUALS IN THE ASSAULTIVE GROUP COUPLED WITH THEIR POOR VERBAL MEMORIES SUPPORTS THEORIES THAT CONTEND SEVERE REGRESSION RESULTS FROM LEFT HEMISPHERE DAMAGE. ALL PATIENTS WERE RECEIVING SIMILAR DOSAGES OF MEDICATION WHEN TESTED, PRIMARILY PHENOTHIAZINES. THIS SHOULD NOT HAVE INFLUENCED THE TEST RESULTS, PARTICULARLY SINCE MANY OF THE IMPORTANT BEHAVIORAL VARIABLES SHOULD NOT BE AFFECTED BY MEDICATION. TABLES AND REFERENCES ARE PROVIDED. (AUTHOR ABSTRACT MODIFIED--MJM)