While critics have recognized the presence of naturalism and Zola's influence in Emilia Pardo Bazan's narrative, they have agreed on the limitation of naturalism in her work as a whole. The result has been twofold: the minimization of the presence of science and the radical division of Pardo Bazan's work. The identification of literary and scientific discourses which occurred in the nineteenth century makes a charting of the discourse of science especially important. This dissertation proposes such a charting through Pardo Bazan's narrative by means of a selection of novels in chronological order Because the literary text weaves an ensemble of discursive practices and participates in a complex social activity, by privileging the theme of disease as operative in the mind/body relationship of the human being and by tracing it through the 'body' of her work, it is possible to map the trajectory of the discourse of science. This approach highlights the active role that scientific methodology played in Pardo Bazan's studies of the dysfunctional human being and the assimilation of contemporary theories within the literary text In two of her early novels, Pascual Lopez and El cisne de Vilamorta, Pardo Bazan participates in a scientific tradition which emphasized the organic aetiology of mental pathology. Disease consists in the individual's identification with anachronistic fictional models. In her 'middle' period, she is concerned with the failure of science as a panacea for national problems. Her vivisection of patriarchy in Los pazos de Ulloa and in Insolacion 'reveals' the underlying mechanism responsible for the 'story' of national decline. La piedra angular represents a continuation of concerns with reform. In La sirena negra, disease becomes one of obsessive self-consciousness. This subjectivity has destabilizing potential for both the individual and for the novela experimental. The novel fragments, and reality is pluralized. In this trajectory, disease has shifted from serving as a cognitive instrument for social analysis to becoming an existential condition; however, the discourse of science is operative from beginning to end. It operates as one more of the discourses which configure the socio-cultural milieu woven into Pardo Bazan's text