ENThe law office of the Grand Duchy of Lithuania, whose official language was Polish, was involved in the process of creating the Lithuanian names. Therefore, there are so many Slavic elements preserved in the names, including the suffixes: -ausk- (-owsk), -avič- (-awicz), -evič- (-ewicz), -ick- (-ick-), -insk- (-ińsk-), -evsk- (-ewsk-). The Slavic lexicon penetrated the Lithuanian common language through the law office, the court and the church. Some of the words became the basis of names, such as: Bačkaitis, Bačkauskas, Bačkevičius, Bačkis, Bačkys, Bačkius, Bačkulis, Bačkūnas, Bačkus, Bačkutis. The history shows that the Lithuanian culture had little influence on the Polish culture; on the contrary, the Polish culture had a big effect on the Lithuanian culture. Throughout the history many Lithuanians settled in Poland and were polonized. Today, only the surnames reveal the Lithuanian origin of some people. In Poland, there are many names that could have been formed only under the influence of the Lithuanian language. They reflect identical or almost identical forms of Lithuanian names (Adomenas, Andrukaitis, Atkaczunas, Augustajtys, Balkus, Degutis), or they retain only some elements of Baltic origin (for example: suffixes -uć, -ejko, ojć, -un, -ul, -Boruć, Kłunejko, Jankojć, Jasielun, Audul). Among the analysed forms there are also names that did not survive in Lithuania, but were preserved in the Polish-speaking environment. In the article, the names are presented in alphabetical order.