This study is conducted to find out the language transfers monitored in the process of teaching Turkish as a foreign language. In the study, language transfers of Belarusian university students who speak Belarusian and Russian as the two official languages while they were studying Turkish as a primary foreign language, were studied throughout analyzing the texts systematically written by the students during the learning process. The main focus of the research is mother tongue interference and language transfer. As it is known, the mother tonque interference can occur positively or negatively in language learning process based on the similarities and differences between the target and native languages. Learners native language comes into power and influences the production in the target language when the learners language skills are not developed yet enough. This is the reason why the negative transfer or mother tongue interference occurs in learners target language learning process. This study as an example of comperative linguistic studies involves language interference analysis between the Turkish that resembles the agglutinating languages and supposed to be a member of Altai group and Russian that resembles the fusional languages which supposed to be a member of Eastern-Slavic group.