The relationship existing between personality disorders (classified according to DSM III) and alcohol treatment outcome was evaluated in 404 alcoholics admitted to the Psychiatric Clinic of the University of Trieste, Italy. One quarter of the subjects had personality disorders, mainly of the 'antisocial', 'dependent', and 'borderline' subtypes. Alcohol abuse was specifically related to 'antisocial' personalities. Marked differences in treatment outcome among personality disorders were found. Group therapy for alcoholism was not beneficial to 'antisocial' personalities; it was most useful among 'dependent' subjects.