Boderline personality disorder cases have been studied in psychoanalysis since the late 1930`s, primarily due to the difficulty they impose on classical analytic treatment. In general, current literature emphasizes the presence of an intense anxiety of being forsaken or invaded, or a state alternating between the two, both of which are commonly associated with faults developed during early experiences with an individual`s environment. These faults, that can be found at a state of total dependency where the baby`s experiences are merged with the mother`s and at a state where the baby understands the mother`s experiences as something separate, implicate in damage to the constitution of potential space between mother and baby and to the constitution of psyche frontiers. Consequently, the patients present deep mental instabilities, relationship problems, strong unreality feelings, among many other issues that can be seen in contemporary psyche illnesses, such as depression, psychosomatic problems, drug abuse, compulsion and eating disorder. Therefore, based mainly on the studies of Winnicott, Anzieu and André Green, this present research proposes that the environment is the basis to a healthy and stable human being`s psyche.