This issue aims to show how the relationship between practice and theory in treatment is so close that the lack of a solid connection to metapsychology could originate a progressive impoverishment of the psychoanalytical work on its whole. The articles of this issue shed a light on both specific aspects of the psychoanalytical practice (e.g. what characterizes an interpretation) and on purely theoretical aspects (e.g. which could be the developments and the appropriate collocation of metapsychology within the scientific sphere). Moreover, a number of ethical and gnoseological traits related to the psychoanalytical treatment are highlighted, traits which are usually ignored not only in the medical psychotherapies but often in the post-freudian psychoanalysis as well.