This paper concerns the reception and dissemination of information in ecclesiastical matters, with specific focus on the Adriatic Sea. As an indispensable tool for exercising power and control, information dissemination can be studied as a way to characterize institutions. This case study of information dissemination during a specific period of Late Antiquity in the regions bordering on the Adriatic Sea, re-examines the commonplace understanding that the church in the West took the place of the Roman imperial state. The study focuses upon the following questions: how did the churches concretely exercise control over their communication networks, what did they borrow from the imperial power, and in what ways did they depend upon the imperial power in doing so? Approaching these questions in terms of the regions which surround the Adriatic Sea is worthwhile because the area, in effect, forms both a border separating and a channel uniting the Greek-speaking East and the Latin-speaking West. The Adriatic offers abundant documentation insofar as its shore belongs to distinct ecclesiastical provinces over which a number of different influences were simultaneously felt: Rome, Milan, Aquileia and Constantinople. A prosopographical study of information agents active in the area will provide data contributing to an evaluation of the quality of the dissemination (speed, routes, efficacy) and of the volume of exchanges, allowing us to measure the evolution of the geography of influence in the region between the fourth and sixth centuries.