This article is referring to the study of the "limit" according to a metapsychological point of view. The main definition of this concept concerns its double possibility to relate and to separate the internal from the external reality. It is about a review of the post-freudian work: the theoretical contribution of the authors P. Federn, D. Anzieu and D.W. Winnicott is viewed through the conceptualisation of the "limit". Also, the study of A. Green, who is the author who proposed not only the concept of the "limit" but also the concept of the "double limit". P. Federn distinguished the Ego in its mental and its physical dimension, in his work which is concentrated on the study of the Ego. According to him, these two dimensions are at the same time related one to the other and seen separately in a healthy functioning psychism. The function of the limit as it is expressed in his theoretical background is absent in the field of psychosis, so according to P. Federn, psychosis is an "illness of the Ego". D. Anzieu expressed the notion of the "Ego-skin" in order to put into theoretical terms its protecting factor considering it also as an analogue with the function of the Ego, regarding the exchanges between the external and the psychic reality. Emphasis is given to the creation of the "Ego-skin" during the first period of life in the relationship between the mother and the infant. Based on the study of the primary period of life, the contribution of D. W. Winnicott concerning the wording of the function of the limit is decisive, as he introduced the theory of the transitionnality, seen as the third reality which is located between the internal and the external reality. A. Green, finally, is the main author who introduced this term as throughout his theoretical work the term got its shape, as he referred to its metapsychological dimension, because the function of the limit is the one which has to be seen as the central dimension of the healthy psychic functioning. Based on this theoretical approach, the psychopathological expression of the concept is studied as well. As a conclusion of this review it is shown that S. Freud was the first who has studied, at least indirectly, the concept of the "limit" by introducing the theory of instincts and throughout his later works.