The following Latin version, hitherto unpublished, of the Byzantine Liturgies of St. Basil and St. John Chrysostom was generously placed at my disposal by my confrère, the late lamented Dom André Wilmart, O.S.B., who about seventeen years ago discovered and transcribed it from a manuscript purchased at London in 1899 by the Bibliothèque Nationale: Nouv. Acq. lat. 1791 Since the manuscript was written in the second half of the twelfth century, this translation is—to put it roughly—at least as old as that of the Liturgy of St. John Chrysostom (= X) made at Constantinople about 1180 by the Pisan interpreter, Leo Tuscus, or that of the Liturgy of St. Basil (= B) made shortly afterward by Nicholas of Otranto. But it is important to note at the outset that the present translation represents a considerably earlier redaction of the Liturgies than do the two aforesaid versions, for we have here, as in the earliest of our manuscripts, the Barberinum S. Marci (= BSM), and several others, the prayers of the celebrant only and a corresponding minimum of rubrics. Of special significance, moreover, are the two following facts: first, the precedence given to B, an arrangement found in comparatively few manuscripts, among them the oldest which we know; and secondly, the occurrence in this same Liturgy of ancient rubrics and of the ancient form of at least one exclamation of the deacon, which point to a very early recension as the original from which the translator worked. On the other hand, over against this ancient form stands a relatively modern text, for not only are certain prayers which appear in the most ancient manuscripts only, missing from this translation, but in those few prayers also in the tradition of which it is possible to distinguish an older from a more recent set of readings, it is the latter which are almost invariably found. Similarly, the indication of certain acclamations by the initial words only (an ancient trait) and the writing out of the ἐκΦωνήσ∊ις in full (a very late practice) constitute another combination of ancient and recent features. But to attempt on the basis of these characteristics to fix the date of either the original or the translation, is to face possibilities only, concerning which it would be useless to speculate.