In the paper, the author deals with two originally Russian handwritten copies of the “Serbian Alexandria”, one of the most popular translated literary works of Old Rus’, judging by the number of extant copies. One of the manuscripts of illuminated “Serbian Alexandria” stored in the collection of the Chester Beatty Library, Dublin (W.151) is recently introduced into the academic use. It should be pointed out that copy of the mid-17th c. is illuminated with the miniatures conveying the characteristics of earlier periods of ancient Russian art. And that raises the question about the time when the protograph of this, without a doubt, copied manuscript had appeared. The Dublin copy refers to the group of illuminated copies of Alexandria, the text of which is of the Barsov type, according to E. I. Vaneeva’s classification, while the monument itself - one of the oldest surviving. Therefore, the author involves in the work a non-illuminated copy from the Russian National Library, coll. of Yu. Yavorsky, No. 41, which includes the already edited text of Barsov type; it means that its dating will be the terminus ante quem for the emergence of the text. The literature gives two different dating of the manuscript, which predetermines the need for its careful study. Careful work with the monument from the Yavorsky’s collection makes it possible not only to solve the problem of its dating, but also reveals a number of features that suggest that the compiler of the part containing Alexandria worked with the Barsov type manuscript, and it was already the illuminated one. This confirms the conclusions of an art critic analysis of the artistic features of the Dublin manuscript miniatures: the protograph of the illuminated Barsov type appeared much earlier than the oldest surviving monument, and it can be attributed to the time no later than the early 17th century.