The aims of the article are to present the development and the degree of representation of individual languages in the Prague printed production of the 16th century and to confirm, or revise, the existing knowledge. The study is also an example of the possible use of the newly created virtual research tool formed within the Knihoveda.cz project. The search interface that is being prepared and is going to be presented to the public in 2020 i.a. provides access to the hitherto separate bibliographical databases Knihopis and Bibliografie cizojazyčných bohemikálních tisků 1501-1800 [Bibliography of Foreign-Language Printed Bohemica 1501-1800]. This will significantly facilitate research into the development of the printed production in the Czech lands in its entirety regardless of language division.