The article is devoted to present the results of ethnomusicological research on parallels in folk song melodies of the Prussian ethnic minorities: Lietuvininkai, Masurians, Kashubians. In the history of ethnic groups of the south part of the West Prussia and East Prussia speaking dialects of the Polish language – Kashubs and Masurs – you may distinguish quite a lot of parallels with the history of the lietuvininkai (residents of Lithuania Minor). A more detailed analysis of the melodies of investigated ethnic groups permits to state that the melodies of the lietuvininkai evidently differ from Polish melodies by the character of intonation, rhythm and performance. Nevertheless, they have intonation complexes, rhythmic elements that are alien to the melodic lines of the lietuvininkai folk songs and could be absorbed from the Polish ethnic music.