The article deals with the Slavonic translation of the Euchologion of the Great Church preserved in two vellum Russian manuscripts of the late XIV — early XV centuries from the State Historical Museum, the Synodal Collection, No. 675 and No. 900. The norms of this translation are similar to those found in metropolitan Cyprian’s translations of liturgical texts. We suggest that the Slavonic version of the Euchologion of the Great Church was composed by scribes who belonged to the Cyprian’s circle but worked under the next metropolitan, Photius, who arranged the dynastic marriage between the Russian princess and the heir of the Byzantine throne. We also surmise that this marriage led to the adoption in the Moscovite Russia of the Cathedral rite of Constantinople, whereas under Cyprian the Athos liturgical traditions were in practice. Some linguistic peculiarities testify Russian provenance of the translation.