ENThe aim of the article is to present a detailed description of the textual structure of Matiasz Czyżewski’s Polish-language anti-Muslim pamphlet Alkoran, published (probably in Vilnius) in 1616 and directed against the Tatars of the Grand Duchy of Lithuania (GDL), and a publication of the auxiliary texts of this early printed book which remains basically unknown. This edition was previously known solely from the old bibliography, where merely its lengthy title was published. The scientific novelty of the present work is due to the fact that it presents a detailed description of the textual structure of Matiasz Czyżewski’s edition based on a well-preserved printed copy identified as a result of archeographic research and kept in the Gdańsk Library of the Polish Academy of Sciences. This printed copy made it possible to determine to what extent the textual material of each of the four main sections (chapters) of this edition was used in a somewhat later book by the author’s brother Piotr Czyżewski’s Alfurkan tatarski..., published by the Vilnius printing house of Józef Karcan in 1616/1617. The main conclusion of the comparative study is that the latter edition most actively used (in a significantly revised form) the textual portions of the second chapter of Matiasz Czyżewski’s brochure, which are directly dealing with the Tatars of the GDL, as well as relatively small fragments of the third and fourth chapters, which, respectively, describe transgressions of the Lithuanian Tatars and advised measures on how to prevent them.mall fragments of the first main section of the Alkoran pamphlet, which tells about Islam in general, are published in the attachment – those that are directly devoted to the Tatars of the GDL, as well as the three auxiliary texts: book’s dedication to the ambassadors to the 1616 Sejm of the Polish-Lithuanian Commonwealth, as well as author’s afterword to the reader and his appeal to the Lithuanian Tatars. Key words: Grand Duchy of Lithuania, polemical literature, early printed books, Lithuanian Tatars, Matiasz Czyżewski, Piotr Czyżewski. [From the publication]