In psychoanalytic theory thanks to S. Freud's explanations of the concept of neurosis, which came into use for the first time in the 18th century by Cullen, the barriers between neurosis and the thoughts which are considered as normal have been removed. Accordingly it is emphasized that neurosis is one of the responses to internal conflicts and the basis of it would be understood in the relationship between analyst and analysand. In order to describe neurosis, concepts such as psychic apparatus, psychic reality, symbolization and choice of neurosis must be accompanied. In this paper, the content of neurosis is illuminated in classical psychoanalytic texts and afterwards, the points of view of post-Freudian contemporary theorists are explained. Furthermore, taking into account the enrichment of psychoanalytic theory with the rise of different pathologies, the idea of removing neurosis from classifications is also discussed.