This paper explores the findings and current state of research on the familial characteristics of persons with borderline personality disorder (BPD). A review of the borderline personality disorder emphasizes the development of the term, etiological issues, and treatment issues related to BPD. Two formal approaches for obtaining accurate diagnosis with a borderline patient are noted. Three major areas of familial characteristics are identified. First, the familial transaction patterns of borderline patients are examined, including the issues of separation and autonomy with the BPD family. Studies are reviewed which suggest that the family environment of the borderline patient does not provide for normal developmental needs in the areas of both nurturance and autonomy. Second, research on the family transmission of BPD is reviewed, including research on both the genetic and the social transmission of the disorder. The final area discussed concerns psychiatric disturbances among family members of BPD individuals. Research is presented which indicates that family members of borderline patients often suffer from significant affective or characterological disturbances. It is noted that the current status of the research suggests that, in a variety of ways, the borderline patient is part of a disturbed family milieu. The need for recognition of the impact of the family system on functioning and treatment is discussed in light of the findings. (NB)