Objectives. – In psychoanalysis, words such as deception, untruth, mythomania or pseudology are generally preferred to the word lying. However, the heterogeneity of the lexical categories used raises an epistemological problem, since it is difficult to determine what distinguishes these notions. This article sets out to list these theories in order to provide an overview. It studies the different approaches to understand what distinguishes and what connects them. The authors likewise explore the reasons why some people exhibit an addiction to lies. Method. – To achieve this, the article reviewsthe different existing theories. It provides a chronologicalstudy of the work conducted on lying from the mid-nineteenth century to the present day. The authors compare and analyze research on the themes of mythomania, deception, untruth, pseudology, etc. The authors propose to refer to the relevant phenomena in terms of “lying”. They discuss the relevance of this notion, which could appear simplistic. Results. – Thus, by close examination of the various theories, this article demonstrates that the conception of lying in fact opens up a new clinical sphere. This contributes to describing the intersubjective dynamics through which people are unconsciously trying to protect themselves from interpersonal ties while at the same time trying to establish them. It is true that this action takes on a transgressive aspect by undermining a primary function of language: connecting people, but the destructiveness inherent in this act appears quite meaningful. The violent emotions raised by a lie take on a messenger dimension. The individual actively passes on to the receiver his own anxieties, and especially his distrust towards ties and language. Discussion. – One of the main problems raised by this clinical field is whether or not the individual intends to fool the person before him. The work on mythomania reinforced the idea that the subject adheres to his fictional scenarios. According to this conception, the individual “lies to himself”, and is not conscious he is fooling the person he is talking to. So, is it possible to make people believe things that are untrue while thinking they are true? This article suggests not. Research on deception shows that the subjects that lie very readily have a remarkable ability for persuasion, to the point that they may obtain the unconscious complicity of their audience. It seems that they possess a very acute sense of the real which can win people over. Paradoxically, their problem could be the fact they are more in tune with the mental world of others than with their own. Nevertheless, a part of the research goes against this viewpoint and some divergences between the theories arise. This is primarily the result of a practical element: the practitioners who deal with this unusual pathology are few. Alongside, the issues faced by these individuals lead them to avoid anything relating to the “psy” culture. In addition, lying is very difficult to observe, which complicates its approach. It is nevertheless easier to perceive when it comes from children. The reasons why they lie are more transparent. The phenomenon has indeed been more widely studied by child therapists. Their work is used here on the basis of the idea that the motivations leading a child to lie can cast light on pathological lying among adults. Lying is a narcissistic solution used to preserve the subject from encroachment anxiety. Conclusion. – This article shows the need to use the notion of the lie to describe clinical situations as yet too poorly studied. This notion unifies a corpus hitherto too broad and imprecise because of the diversity of the lexical categories used. From a clinical standpoint, it provides better understanding of the compulsion to lie to other people. By categorizing liars as impostors, or as mythomaniacs, there is a danger of obliteration of the transference-cons-transference dimension of their behavior.