St Ambrose’s teaching on the Eucharist is largely found in his De Sacramentis and his De Mysteriis, but occasional references to his Eucharistic theology also occur in his other works. This Short Communication will explore his comments on the Eucharist as found in his twenty-two homilies on Psalm 118 and his Commentary on Twelve Psalms. The Scriptural support and orchestration used in his synthesis on the Eucharist in these Psalm commentaries will be noted, as will be his identification of Old Testament prefigurements of the Eucharist. The manner in which Ambrose identifies specific fruits or effect of the Eucharist in the lives of its recipients will be explored. Finally his many references to the poculum inebrians will be examined with reference to their complementary application both to the Eucharist itself and to the Scriptures in the life of the faithful.