The article deals with the medieval manuscript library of the former house of the Canons Regular of St Augustine in Prague-Karlov. The text presents extant sources: apart from the manuscripts themselves, some of which contain ownership and donation records, there is in particular a medieval list of Karlov manuscripts, made by the abbot Procopius in 1380, and a record of the donation of a large number of codices given to the library by Jan, the parish priest of Dobešov and Černovice, in 1395. The article further analyses them and describes the history of this library on their basis. The core of the study is a description of the surviving part of the library, from which twenty-five manuscripts have been identified. It summarises the physical characteristics of the codices, their dating, provenance, and language classification. Most attention is given to a detailed thematic categorization of the library’s contents.