The article compares the text of the „Vidin“ service for St. Petka Tărnovska (Paraskevi of Epivates), featuring a canon for the eighth mode, and the text of the Saint’s service known by three Russian copies in 16th–17th-c. manuscripts from the Trinity–Sergius Lavra. The main peculiarities of the 15 known South Slavonic transcripts of the „Vidin“ service (14th–17th cc.) are analyzied and there are underlined the main stages in the development of the text. It is concluded that the Russian copies are closest in composition and structure to the earliest Bulgarian copy in the 14th-c. manuscript Sinai 25, with added stichera and glories, known from Serbian copies from the 15th–16th cc., and a new kondakion. The Russian copies show that the „Vidin“ service was early included in Russian liturgical practice. It can be assumed that it was done by Gregory Tsamblak who introdusted the cult of Petka Tărnovska to the Orthodox Christian population in the northeastern Slavic lands. The Russian edition of the service for the Venerable Paraskevi-Petka from Epivates, preserved in a 1645 printed menaion, again from the Trinity-Sergius Lavra, contains in addition to the canon for the eighth mode a different canon for the sixth mode (instead of the canon for the sixth mode known by the Menaion of Dragan). The new six-mode composition was created in the 17th c. by adding, reworking and adapting other texts, as shown by its distinction from the 16th-17th-c. Cyrillic copies originating from the Polish- Lithuanian Commonwealth.