Abstract: A Leningrad composer, music historian, conservatory professor Feodosii Antonovich Rubtsov (1904 - 1986) worked with the Union of composers for more than 50 years. Not only did he edit compositions and prepare musical and piano scores for publication, he also headed the department of music folklore. There he studied, gathered and used the genuine pieces of folk music culture. Rubtsov gave special attention to attracting young musicians - composers and music historians, students of Leningrad conservatory - to working with folklore sources, in order to use them in compositions and to study. The author of the article analyzes the documents kept in the Archive of Saint Petersburg Conservatory named after N.A. Rimsky-Korsakov and the Central State Archive of Literature and Arts of Saint Petersburg to unveil this poorly studied part of Rubtsov’s work. The author introduces into scientific discourse the transcripts of the records of meetings and reports of the music folklore department of the Union of composers proving that the department (and the folk music panel) was solving urgent tasks of creating a public fund of expedition recordings and music folklore library, organising expeditions and interaction between folklore specialists of various scientific and educational institutions, preparing publications about music folklore, etc.