Among its various and important funds, the Este University Library contains a wide and homogeneous collection of music manuscripts which constitutes an essential source in order to retrace the history of music in the period going from the 15^th to the 18^th century. The collection increased over the years until the 19^th century. An important part in its increasing process was played by the duke Ercole I (1471-1505) and the duke Alfonso II (1559-1597) when the Este court was based in Ferrara. Then, after the Este family moved to Modena, Duke Francesco II (1662-1694) reinforced the Este patronage in the music field. Today, the music fund contained in the former Duchy library mostly preserves its 18^th century aspect. There are some relevant handwritten codes dating back to the Ferrara ruling period realized for the Duchy chapel founded by Marquis Leonello in the half of the 15^th century. The collection also contains several madrigals and some handwritten codes dating back to the period of Duke Alfonso II. The fund left by Duke Francesco II is only in part related to the Modena production. It reflects a great collection interest and the desire of providing a wide documentation of the contemporary music activity.