The study relevance is caused by the special language situation in Belarus which is in close attention of modern linguists for several decades. Russian-Belarusian languages interaction is a special type of bilingualism which has specific features due to the common fate of the Belarusian and Russian people, genetic relationship, and language systems kinship. In Belarus the processes of generation and perception of the text in Russian language take place against a special psychological background of the Belarusian language system which creates the effect of the so-called unbalanced bilingualism. As a result one language system comes into contact with another causing interference. A serious problem in Belarus is the spontaneously russified version of the Belarusian language - Trasyanka. The goal of author is to identify the main problems of foreign students’ language adaptation in conditions of Belarusian-Russian bilingualism. Studying Russian in Belarus foreign students have to deal with texts in the Belarusian language, with colloquial speech and, of course, use words, terms, names in the Belarusian language. The author comes to the conclusion that foreign students do not experience any special communication difficulties from the Belarusian language unfamiliarity. The teacher of Russian as a foreign language, however, has a different, special task - to ensure a harmony among the culture of the language being studied (Russian), the culture of the host country (Belarus) and the national culture of the student.