This article develops the ‘ethical’ implications of Otto Fenichel's (1897-1945) views on the practical purposes of the psychoanalytic knowledge and the therapeutic function of psychoanalysis, since Fenichel elaborates a psychoanalytic practice conception that is worth revisiting from a sort of debate that refers to a ‘psychoanalytic ethics’ the problems of psychoanalytic practice. In order to fulfill this goal, what is proposed herein is a historical and theoretical investigation of Fenichel's conceptions from a structural reading of his work, examining the internal architecture of his arguments and concepts in the light of works as a whole and the context of such production. First, context is provided for Fenichel's conception of psychoanalytic practice amidst institutional disputes of the European and American psychoanalytic movement. After that, there is a discussion on Fenichel's 'dialectical-materialist Psychology’ project to extract the author’s conception of psychoanalytic knowledge. In a third step, it is presented how Fenichel's conception of psychoanalytic knowledge serves as a central piece of his understanding of psychoanalytic practice. Finally, after locating Fenichel's notions about the practical purposes of psychoanalytic knowledge and about the therapeutic function of psychoanalysis, it is developed the ethical implications of Fenichel's conception of psychoanalytic practice.