The first part of this text is dedicated to theoretical and metapsychological reflexions. After having situated the essential of what inscribes the borderline states in the heart of the fundamental and actual psychopathology, the author studies two big problematics that the borderline states convoke: 1. The problematic separation anxiety and its specific variations in the constitution of internal and external reality. 2. The problematic of psychosexual organisation, essentially articulated with masochism. The way in which the two problematics articulate and particularly the links between love and hate that prevent the access to ambivalence. The second part of the text treats psychoanalitical clinics and also the negative therapeutic reaction, which manifests itself preferentially in the cure of borderline functioning. The place of the pain in the transference constitutes one of the main axes of fragments of analysis proposed.