• The lifetime expectancy (morbid risk) of alcoholism was determined in the parents and siblings of 83 women with DSM-III borderline personality disorder and compared with that in the parents and siblings of 100 women with DSM-III schizophrenia and 100 women with DSM-III bipolar disorder. The relatives of the borderline probands had two to three times more alcoholism than the relatives of the bipolar and schizophrenic probands. The condition was most common in the fathers of the borderline probands, almost one third of whom were either alcoholics or heavy drinkers. When the three groups of probands were subdivided according to whether they, themselves, had occasionally abused alcohol, there were no longer any significant differences in alcoholism among their relatives.