ENThe Grand Duchy of Lithuania, due to its inner organisational model ñ a multinational, multilingual and multi-religious state ñ and the geopolitical situation was compelled to employ multilingualism to maintain internal and external communication. Bilingualism and sometimes multilingualism were also characteristic of GDL Western Catholic churches. The paper analyses the manifestations of bilingualism in the scriptures of the GDL Roman Catholic church with the focus on the documents of ecumenical visitations to parish churches. During the visitations of high-level church officials to the parish, a thorough examination and detailed description of the church building, its equipment, liturgical accessories, the buildings and property of the rectory, etc. were carried out. Nowadays, the old visitation documents are significant not only for the history of specific parishes and the analysis of material culture and art heritage or for the cognition of other regional organisational models, but also for the perception of the linguistic situation and the level of linguistic education in GDL. As Latin was the language of the Catholic church, the documents of visitations were written in this language. Still the visitation process itself ñ presentation, registering and directions ñ combined verbal, visual and written communication. The result of this communication had to be presented in Latin.The analysis of old visitation documents discloses lexical and grammatical shifts between different (most often Latin and Polish) languages in the process of communication during visitations. As Latin was not native to those participating in the process of visitation, the language of documents could be seen as the expression of additional multilingualism. In addition, communication itself was carried out in two languages during visitations; therefore, documents could be treated as a result of the translation process. It explains the locality of loanwords (both from Latin to Polish, and from Polish to Latin), the amount of macaronisms (mechanically inserted foreign language words in an unchanged form) and entire paragraphs in the alternative language. Thus, if a scribe did not know the Latin name of a specific thing or colour, he would simply use the Polish one, e.g. the Polish loan word in Latin: carbona or a macaronism: marginibus additae latiores korunki. Sometimes, for the sake of clarity, the equivalent in another language is presented: cum lapidibus rubeis vulgo duplet. With Polish taking prevalence in record keeping, the situation of bilingualism in visitation documents remains. Only this time Latin is used for the realisation of clarity and concreteness criteria.