The term Russianism refers to words of Russian origin that underwent the process of transition from the foreign word to the word that forms the constituent part of any language and it includes three degrees: model, compromise replica and replica. According to Filipović, it is necessary to include four levels of adaptation in order to integrate a Russian word into Croatian language, those four levels are orthographic, morphological, phonological and semantic. This diploma thesis represents and elaborates the adaptation of Russianisms on the phonological level. Through the procces of transition from the model to replica, phonemes of the language donor are in correspondence with the phonemes of the language recipient. There are two processes that enable the adaptation and these ate improtation and substitution. According to Filipović, the process of substitution is called transphonemization and it elaborates three different types of adaptation on phonological level such as: zero (it represents Russian phonemes that have an equivalent in the Croatian), partial (represents Russian phonemes that do not have a proper equivalent, but may be replaced by another phoneme) and free (represents Russian phonemes that have no equivalent) transphonemization. There are improtant differences between two languages that have an effect on phonological adaptation and these are reduction that is present in Russian, palatalization of consonants and the accent.