The article is devoted to the evolution of the Roman primacy in the 4th century. The Christianization of the Empire accelerated the process of regional consolidation of the episcopate, but did not lead to the emergence of speciﬁc «imperial ecclesiology». At the same time in the 4th century, traditional apostolic ecclesiology has maintained its position both in the West and the East. We can distinguish two diﬀerent types of the apostolic ecclesiology: locally-historical (the doctrine of St. Irenaeus and Tertullian) and universally-hierarchical (the concept of St. Cyprian of Carthage). The ﬁrst can be ﬁ nd in the works of pope Julius, St. Athanasius and in the letter of the council of Constantinople (382), the second — in the texts of St. Basil the Great and Palladius of Ratiara. At the same time on the council of Serdica (343) Western bishops supported the new “Roman” ecclesiological model. They proclaimed the Roman See as the Chair of Peter the only center of catholic communion and invested it with special legal prerogatives. In fact, this model was the result of ecclesiological synthesis of two early conceptions of apostolicity: the idea of apostolic origins of the Roman Church was connected with the idea of the primacy of Peter as the basis of the Church’s unity. In the future, this conception was adopted by the bishop of Rome. Pope Damasus I (366–384), developing the doctrine of the Roman See as sedes apostolica, actually put principle of Roman primacy above the principle of synodal consensus. Eastern bishops did not support this interpretation of the church order, defending the autonomy of the Eastern Churches. They proclaimed Constantinople New Rome, in fact, denying the uniqueness of the status of the Church of Rome.