ENThe article discusses the sources of the chronicles of Motiejus Strijkovskis (Polish: Maciej Stryjkowski, Latin: Matthias Stricovius, Matys Strycovius, Matys Strykowius, etc., 1547–c.1593) and Alessandro Guagnini (full name: Alessandro Guagnini dei Rizzoni; 1534 [1538]–1614), which were cited by Simonas Daukantas. Daukantas wrote four works of a historical nature and quoted Strijkovskis in all of them; as for Guagnini’s chronicle, he did not quote it in his first work Darbay senuju Lituwiu yr Zemaycziu (The Deeds of the Early Lithuanians and Samogitians, 1822; hereinafter Darbai) and in his last work Pasakojimas apej Wejkałus Lietuwiû tautos senowie (A Narrative about the Deeds in the Ancient Times of the Lithuanian Nation, ~1850–1854; hereinafter Pasakojimas). The question is raised whether the ambiguous evaluation of the authorship of Guagnini’s Sarmatiae Europeae descriptio (1574–1578; hereinafter SED) might have influenced Daukantas, which led him to rely more heavily on Strijkovskis’s work during certain periods of the writing of his historical works. In order to determine the extent to which Daukantas was aware of Strijkovskis’s accusation of plagiarism against the Italian chronicler, the dynamics of the (non) citation of the works by these two authors in Daukantas’s works and in the excerpts from books are discussed.Since Guagnini’s work (and its fragments) was more frequently reprinted in Europe, even though its authorship was raising doubts, researchers are facing difficulties as to the source of citations. The article discusses the editions of fragments of Guagnini’s SED and establishes that Daukantas translated Guagnini’s ‘Ducatus Samogitiae’, which he used in BUDĄ Senowęs-Lëtuwiû Kalnienû ĩr Ƶámajtiû (The Character of the Early Lithuanians, Samogitians, and Highlanders, 1845; hereinafter Būdas), from the first edition of the 1627 book RESPUBLICA, Siue Status Regni POLONIÆ, LITUANIÆ, PRUSSIÆ, LIVONIÆ etc. diuerſorum Autorum compiled by Johannes de Laet. As the first edition of Strijkovskis’s Kronika was difficult to obtain in the nineteenth century and almost impossible to use and read due to its poor condition, it is assumed that Daukantas did not have access to the first edition. The research shows that in his Darbai, Istorija žemaitiška, Būdas and in his notebook Išrašai iš knįgų apie etnografje ir istorje in quoro 28 (Excerpts from Books on History and Ethnography in quoro 28), Daukantas quoted Strijkovskis’s work from the 1766 edition, which differed from the first edition of 1582 in its structure and textual presentation.In his last work, Pasakojimas, Daukantas relied on the edition of Strijkovskis’s Kronika Polska, Litewska, Żmódzka i wszystkiéj Rusi (Chronicle of Poland, Lithuania, Samogitia, and the Whole of Rus) edited by Mikołaj Malinowski. In the introductory word, Malinowski referred to research by Józef Ignacy Kraszewski and Ignacy Daniłowicz and dealt extensively with the issue of plagiarism. In Pasakojimas, Daukantas no longer cited Guagnini’s chronicle, but presumably not because of the accusations against the Italian chronicler. Daukantas did not quote this work because it did not deal with the developments of the sixteenth century, and the chapter on the nature of the Lithuanians was too much abridged. [From the publication]