The prevalence of DSM-III-R self defeating (masochistic) personality disorder was determined on an outpatient population (N = 82) and a normal population (N = 40) using the Personality Diagnostic Questionnaire (PDQ). Fifteen (18.3%) of the outpatients and two (5%) of normals were assessed as having the disorder. Overlap of greater than 50% with borderline, avoidant, and dependent personality disorders was found. Validation of masochistic personality disorder will require it to be of value in research and clinically in ways distinct from the other personality disorders with which it is associated.