Leonine Sacramentary is one of the oldest sacramentaries which is generally believed to be from the fifth century. Though the original Leonine Sacramentary remained in manuscript form, it was printed for the first time only in 1735 by the effort of G. Blanchini. He attributed this sacramentary to Pope Leo (440-461) and gave the title “Old Sacramentary of the Roman Church Composed by Pope St. Leo I”. however, later studies revealed that this sacramentary was not entirely composed by Pope Leo I personally but it may contain some prayers composed by him. In the light of similar studies, J. Assemani rectified the previous erroneous title in 1749 and called his edition “Sacramentary of Verona,” because it is a manuscript written in Verona in the first quarter of the seventh century after the ancient Roman model (c. 5th century) which is lost. It is preserved in Verona to this day. In the fifth century each stational church in Rome had its own booklet for Mass (libellus missarum), presenting orations for solemnities and saints associated with the church. The Leonine Sacramentary, preserved in Verona manuscript from early 7th century, is actually the 6th century collection of these individual booklets (libelli). L.C. Mohlberg has showed that large portion of the beginning of the sacramentary is missing and all the visible traces of the collection of libelli and the origin of the book have disappeared.
Leonine Sacramentary contains 1331 prayers mainly orations and prefaces for various Masses. These prayers are not organized for the direct use in the liturgical celebrations because the prayers are arranged according to civil calendar and not liturgical year. The plan in the critical editions published indicates that each month included several formularies for the same feast. Hence scholars like Palazzo argue that it was a careless compilation of libelli. This observation explains why Leonine Sacramentary did not have any direct descendent and was quickly replaced by more thoroughly organized works such as Gelasian and Gregorian Sacramentaries.
Nevertheless, Leonine Sacramentary is important from historical and liturgical perspectives, because it sheds light on worship in the city of Rome in the early days and it is the only material witness for the transition from improvisation to codification through liturgical books. Liturgical research has identified that a great part of its contents are found in the later sacramentaries in a different form of organisation and arrangement. As Vogel and Palazzo observe, until recently liturgical historians believed that the various types of sacramentaries succeeded one another in time, whereas in fact they exchanged material, influenced one another, and appeared roughly at the same time within different settings of celebration such as papal or presbyterial.
 E. Palazzo, A History of Liturgical Books from the Beginning to the Thirteenth Century, trans. M. Beaumont (Collegeville, MN: The Liturgical Press, 1998), 39.
 Encyclopaedia of Early Christianity, 810; D.M. Hope, The Leonine Sacramentary: A Reassessment of its Nature and Purpose (Oxford: Oxford University Press, 1971), 16, 23; C.L. Feltoe, Sacramentarium Leonianum: Edited with Intorduction, Notes and Three Photographs (Cambridge: University Press, 1896), viii.
 L.C. Mohlberg, ed., Sacramentarium Veronense (Rome, 1955). See also J. Pinell I Pons, “Teologia e liturgia negli scritti S. Leone Magno,” EO 8 (1991): 137-181.
 C. Vogel, Medieval Liturgy, 62-63.
 E. Palazzo, A History of Liturgical Books, 42.