According to Jerome, Fortunatian’s commentary on the Gospels was written during the reign of Constantius II (337-361). Like many exegetical works, it offers little evidence for dating, but a careful analysis of the elements which relate to the Trinitarian polemics allows us to relate various parts of the commentary to events or creeds of the 350s, suggesting that it was written between 353 and the terminus ad quem 360. The study of these elements also makes it possible to clarify Fortunatian’s theological position, which is faithful to Nicene conceptions while allowing for an accomodation to the Homean line promoted by Constantius and the bishops of his court.