Bulgarians have been transcribing their musical folklore since about the middle of the 19th century. It is a music teacher who first wrote the notation of folkloric songs in asymetric times – 5/8 and 7/8. In the early 20th century Bulgarian musicians already noted all asymetric times. In the twenties Vasil Stoin and his collaborators travelled through the country and collected thousands of songs in each dialect that they compiled in voluminous books. The creation of the Music Institute in 1948 gave an impetus to research work and collecting. That of the Institute of Folklore in 1972 enabled to better control this research work. The archives of the Bulgarian Academy of Sciences contain more than 250 000 folksongs and pieces of instrumental music, folk dances, films on ritual practices with musical accompaniment.