The authors point out that in Freud's thought fantasy surpasses ontogeny, becoming history of phylogeny through collective and prehistoric Oedipus. Unlike Freud, who followed a positivistic epistemology, the authors emphasize the individual meanings of fantasy, according to the present constructionistic epistemology. – First, an outline of this point of view is presented. Secondly, a theoretical approach between fantasy and repression-in the light of the concept of >compulsion to know<-is suggested. A clinical vignette follows to illustrate the above mentioned principles.