Through the analysis of the literary fictional fairy tale (that is without traditional origins) which spread in Italy in the post unification period, the A. reveals important connection between this genre and the peculiar scientific culture of nineteenth-century Positivism. In a period when frequent mutual exchanges between literary authors and scientists made it possible to find scientific theories and the cutting edge inside popular narrative and, likewise, to find literary passages in popular scientific treatises, the literary fairy tale does not make an exception. On the wake of recovering the oral traditions – with which anthropologists, ethnologists and demo-psychologists were busy – the fairy tale represents the perfect trait d’union between folkloric tradition and literature, between narration and medical scientific observation. Authors like Emma Perodi, Luigi Capuana, Giuseppe Pitré reintroduced, to the Italian public, the genre of fairy tale, following the characteristic rule of the nineteenth century Fantasy and linking the neo-Gothic foreign literary movements, and the horrid sense of a not yet vanished Romantic literature, with the new cultural trends. Thanks to an in the depth study on this literary genre, the A. – in addition to reaffirming the same connection of literature with the contemporary scientific spirit and with the popular tradition as well – leads us in disclosing in part the deepest origins of the modern fairy tale.