This study focuses on the manuscripts of the library of the Piarist College in Mikulov which is kept at the Moravian Provincial Library in Brno as a closed holding. The inventory is based on an old manuscript inventory compiled by Vladislav Dokoupil (1918–1992) which, however, has been adapted, completed, and extended substantially by a historical commentary. In the commentary the author tries to determine the origin of the manuscript collection by analysing preserved manuscripts and other archival material of Piarist provenance.