The results of research into the history of Polish music in the 20th century have considerably broadened our knowledge of this area of national culture. Many publications about the first capital of Poland either did not deal with this field at all or dealt with it in a very fragmentary way. The discovery in 1957/58 of a rather rich collection of musical works from the repertoire of the Cathedral's instrumental and vocal ensemble provided an incentive to study the archival collections kept in the Archdiocesan Archives in Gniezno. This article is an attempt to present the unknown history of the cathedral music ensemble in the city of Lech.