The author describes the complex system of phantasies related to the reality of dirt which manifest themselves both in the structure of neuroses and in many significant aspects of normal adult life. The following subject headings show the scope of the discussion: The body as a dirt factory; Protection of the outsides from the insides; The unconscious hierarchies of dirt; The taboo on the apertures; Compulsive cosmetic compensations in woman; The forbidden interest in excretory functions; The relation to unreality feelings in women; Genitals as excrement; Sociological significance: the stratification of society; Family pride and shame; Critical review of the treatment of the concept of dirt in psycho-analytic literature; Redescription of the development of excretory habits and