Clinical material from the psychoanalysis of a 6-year-old boy is presented which manifests the creation of an anal psychic world—a psychic world which is blatantly anal in content and characterised by the formal qualities of de-differentiation and interchangeability, which are linked to anal experience and the level of cognitive maturation typical during the anal phase. This case demonstrates the existence at an earlier developmental level of perverse qualities which have previously been identified in adults. In particular, similarities are noted with the fantasies of adult perverts and the Marquis de Sade. Psychodynamic antecedents which have previously been extrapolated from investigation of these adults are confirmed in statu nascendi in this child. Like adult perverts, this boy appears to have created his anal world to defend against acknowledgement of sexual and generational differences. His anal world play is conceptualised as an example of a perverse play style.