On the basis of well-known hagiographic, diplomatic and sphragistic sources, this paper reconstructs the presence and significance of the cult of Saint Isauros in Durres. The sources show that this saint, martyr from the time of the emperor Numerianus, was venerated in Durres from the beginning of the eleventh to the end of the fourteenth century. Together with Saint Asteios, the Bishop of Durres, he was the patron of the Cathedral of Durres, which indicates the special importance of Saint Isauros’ cult in this city.