This article presents a comparison of the two Church Slavonic versions of the Acts of the Apostles with commentaries (on Acts 13:4–28:10), that is, the so-called middle Bulgarian translation (made in the 14th century probably in Tarnovo) and the translation made by Maximus the Greek in the initial period of his translation activity in Russia (in 1519 or 1520). Two lexical regionalisms were found in his translation: zakladniki ‘hostages’ and poslaniya berestenye ‘birchbark letters.’ Their usage relates to the activities of Maximus’ Russian helpers, especially the work by Vlas Ignatov. The corresponding fragment is correlated with the explanatory version of the Book of Isaiah, which emerged in Preslav. A comparison of this text by Maximus the Greek with the explanatory translation of the Book of Isaiah shows that Maximus did not utilize the old (Preslav) version. Therefore, this fragment is new in relation to previous Slavic traditions of translation. The analysis of the final part of the text leads to the conclusion that the translation of the Acts with commentaries has been revised according to the Greek original from the thirteenth chapter to the end.