The article is devoted to the results of ethno-musicological research on historical parallels between the publication and studies of Lithuanian and Polish folk songs. Lithuanian and Polish folk songs represent significant integral part of the musical folklore of those nations. They reflect common national and regional features of the world outlook and the mode of artistic expression of the folklore performers in different countries. Both Lithuanian and Polish folk songs have been published in different publications starting with the 18th century, and from the 19th century they started appearing in reputable many-volume collections of songs. Those were abundant, diverse, and manifold folklore materials that have been an independent object of research for several centuries. However, comparative studies of folk songs of both nations, of their lyrics and melodies, represent a totally new field of study.