This thesis traces the paths of the production and criticism of science-fiction literature in Brazil from the middle of the nineteenth century to the present. The goal is to investigate the process of marginalization of the genre from the standpoint of the construction of Brazilian literary canons, roughly divided in two branches: the high canon, which legitimates the Brazilian intelligentsia by relating it to European high culture; and the popular canon, mediated by the same intellectual elite, which ideologically affirms Brazilian myths of nationality. The analysis of critical discourses about science fiction shows this duality, in addition to some of the values, assumptions and practices that regulate the processes of literary canonization in Brazil. The questioning of these parameters is a key way to understand the non-assimilation of the genre by the official canon, which politically constructs the idea of a Brazilian literature.