Foreign language learning is a very complex process that is influenced by many factors, including the individual's mother tongue as well as all other languages ​​that the individual has learned by the time they start learning a new language. The influence of knowledge of one language on learning another is called crosslinguistic interference and this phenomenon is the topic of this thesis. The first part of the paper includes the theory of crosslinguistic interference, as well as the terms transfer, interlanguage and contrastive analysis. In this section you can also find an overview of previous research on crosslinguistic interference. The second part is dedicated to research conducted at the Faculty of Humanities and Social Sciences on a sample of 36 students of Russian language and literature, of which 21 were third-year students and the remaining 15 were fifth-year students. The aim of the research was to check the negative impact of knowledge of the Croatian language on the acquisition of the Russian language, that is, how many mistakes that students make when translating can be explained by croslinguistic interference. Also, the aim of this research was to check the connection between factors such as the level of knowledge of the Russian language, students' interest in the language, and awareness of the possible negative impact of the mother tongue on learning a foreign language with the occurrence of crosslinguistic interference. The results of the research showed that errors caused by crosslinguistic interference make up more than a third of the total number of errors and that students whose knowledge of Russian is at a higher level and those who feel more interest in learning make on average fewer errors, but the percentage of errors caused by crosslinguistic interference is higher than other students. According to the results, awareness of the possible occurrence of crosslinguistic interference did not affect its occurrence. The results of this research indicate that crosslinguistic interference presents a problem for all students, regardless of their level of knowledge, and that as such this phenomenon deserves more attention in the process of learning a foreign language.