Patients with the borderline syndrome, although not always the sickest patients, often cause the most difficulty because of their intense and contagious affects, their often impulsive behavior, and the strains they place on the treaters' countertransference. The author explores the hitherto ignored area of medicolegal problems that often arise in treatment of borderline patients. Specifically, he addresses the issues of legal ignorance of the syndrome, the effect of dynamic processes such as splitting and psychotic transference, problems regarding limit setting and related management approaches, and problems arising from countertransference phenomena. He suggests approaches to these problems as well.