Maciej Stryjkowski is a well-known historian and poet of the Renaissance, but one aspect of his work has remained underexplored – namely, his material on Lithuanian folklore. Stryjkowski adapted authentic 16th century Lithuanian military-historical folklore in his historiographical works. Its elements are included in his works O początkach, wywodach, dzielnościach, sprawach rycerskich i domowych sławnego narodu litewskiego, żemojdzkiego i ruskiego and Kronice Polskiej, Litewskiej, Żmudzkiej i wszystkiej Rusi. While ritual folklore has attracted the attention of researchers, Lithuanian military and historical songs recorded by Stryjkowski, although noted, have hardly been researched. This article analyses several manifestations of such folklore. The material recorded by Stryjkowski brings new insights and allows us to expand our knowledge of the events recorded in the legendary part of Kroniki litewskie. At the same time, the article discusses the authenticity of the sources Stryjkowski drew on, using the example of songs of a military and historical character concerning the Giedroyc family, confirming that folklore of a military-historical nature existed in Lithuania before the 16th century.