In order to examine the symptom characteristics of borderline personality disorder (BPD) and schizotypal personality disorder (SPD), 45 male inpatients with DSM-III personality disorder diagnoses, including patients with SPD (n = 15), BPD (n = 17), and both SPD and BPD (BPD/SPD) (n = 13), were administered a battery of psychological tests that included measures of traditionally defined schizotypal features such as perceptual aberration and anhedonia (the Chapman Psychosis Proneness Scales) and borderline characteristics such as impulsivity (the Barratt Impulsivity Scale) and hostility (the Buss-Durkee Hostility Inventory). All patients also completed the MMPI, which includes scales measuring schizotypal features such as endorsement of quasi-psychotic experiences in addition to scales measuring impulsivity and aggression. Both BPD and SPD/BPD patients were discriminated from SPD patients by significantly higher levels of impulsivity and aggression but not by the differential presence of psychoticlike symptoms or anhedonia. Additionally, patients meeting criteria for both borderline and schizotypal personality disorders (SPD/BPD) exhibited a consistently more impaired profile on psychologic measures of both borderline and schizotypal features, as compared to patients with BPD or SPD. The findings are discussed with regard to the proposed DSM-IV symptom criteria and in terms of traditional conceptions of both borderline and schizotypal personality disorders.