The aim of this paper is to show the new literary direction naturalism and its influence on the literary work of Eugen Kumičić. The parallel development of two literary trends in Croatia, realism and naturalism, gave rise to a multi-year polemic that shook the Croatian literary scene. Criticism focused on Eugen Kumičić's attempt to introduce naturalism as a dominant direction in Croatian literature, which, in their opinion, did not agree with our traditional style of writing based on the example of Šenoa. In naturalism, literature had the function of presenting events as they are, with all the ugliness and negativity, and the writer was supposed to be objective. Kumičić was largely guided by Zola's ideas, which he tried to implement in his works, primarily in Gospođa Sabina, which abounds in naturalistic elements, which is shown in the analysis of the work. An analysis of the work Olga and Lina, his first naturalistic work, was also carried out. Kumičić also managed to show naturalism in the historical novel Urota Zrinsko-Frankopanska, which is also visible in the analysis. The naturalistic elements that can be seen are power, money, corruption, manipulation, Zagreb's elite citizenry, the difference between the rich and the poor, a detailed depiction of cities, spaces, but also the depiction of the death of noble families down to the smallest detail. Kumičić writes a critique of society, but also raises citizens' awareness of the importance of freedom. Although Kumičić was considered Zola's successor, analyzing his works it can be said that they still exude the Šenoin tradition guided by realism along with elements of Zola's naturalism. Ante Kovačić moves away from the Shenoin conception of writing and tends towards criticism of society. Naturalistically depicts the village-town relationship and the transformation of peasants into citizens.