The “Liturgy of Saint Gregory the Great” was most widely used among the Latin speaking churches of the West. However, Gregory’s Liturgy also existed in a Greek translation and found usage within Greek speaking churches. Previous to this publication, the Greek text was not widely available to scholars and was not based on the best manuscript. Thus, Anton Baumstark presents here the complete Greek text of the Liturgy. In his introduction to the text, Baumstark discusses the relationship between the Greek and Latin versions as well as the possible historical circumstances of the Greek version. This article is a valuable resource for the study of the transmission of liturgies throughout the Mediterranean world of late antiquity.