My proposed PhD, titled Zola's Naturalism in The Rougon-Macquart: The Fatality of Sexuality, aims to study the basics of the naturalistic novel in the second half of the nineteenth-century France. Firstly, I have looked back at previous critical studies that were dedicated to the themes of sexuality and/or fatality in Zola's writing. This introductory chapter helped me understand how far critics have gone and what a long way we still have to go before we can fully appreciate the importance of these themes in the context of naturalism. Throughout the twenty novels that make The Rougon-Macquart series, I studied the fictional characters in their being, their appearance and their evolution in space and time. I therefore investigated whether or not these characters were masters or slaves of their space and time and beyond that, what influences they had on each other. Afterwards, I questioned the fecundity of the theme of sexuality in Zola's work to find out both the aspects of originality in his writing and his contribution to the modern novel. Nevertheless, I have criticized Zola on a wider angle as an emeritus writer with his own "weaknesses". Methodologically, I have largely used the semiotics approach along with psychoanalysis due to the specificity of sexuality. Despite the wide range of critical studies on Zola's novels, in my sense, most of them have so far failed to tackle naturalism at its foundations, i.e. sexuality. In fact, if one attempted to free The Rougon-Macquart from the theme of sexuality, neither the Rougon-Macquart family would exist nor the twenty novels they generated. Studying sexuality therefore appeared to be essential to the understanding of the naturalistic theory. However, and surprisingly so, most of Zola's critics have avoided that inescapable theme, perhaps more likely for reasons of decency rather than for scientific ones. It is in such context that I have decided that it was time to bring it to light for the sake of truth about the knowledge of Zola.