Hilary of Poitiers is perhaps the most neglected of the great Patristic theologians. In particular, there has been little detailed analysis of the biblical interpretation that provides the central strand of his theological mind. His work on St. Matthew is almost the first extant commentary in the Latin West. It is analyzed here, with a survey, for the first time, of the growth of the commentary as a literary from. The relation between exegesis and theological method in his later work on the Trinity and the Psalms shows the development of his techniques and their theological consequences. The concluding sections provide a critical evaluation of the role of Patristic material in contemporary theology, with reference to the still intractable problem of the precise uses of the Bible in theology.