The importance of interpersonal relationships for the organization of the psychiatric hospital as a therapeutic setting is presented through the theoretical framework of object relations and milieu therapy. From the point of view of psychodynamic approach the majority of hospitalized patients show the pathology of self and object relations. So, the familiarity with these theories for the optimal planning of treatment of these patients is of a particular importance. The concepts of following authors are discussed in this paper: Winnicot, Kohut, Mahler, and Klein, as well as a concept of projective identification and milieu therapy.