The Martyrologium Hieronymianum (meaning "martyrology of Jerome") was a medieval list of martyrs, one of the most used and influential of the Middle Ages. Compiled probably in the late 6th century by anonymous monks in Gaul from calendars or martyrologies originating in Rome, Africa, the Christian east and locally, Martyrologium Hieronymianum was the first general or "universal" martyrology, and the ultimate source of all later Western martyrologies.
Attributed to Saint Jerome, the MH contains a reference to him derived from the opening chapter of his Vita Malchi (392 AD) where Jerome states his intention to write a history of the saints and martyrs from the apostolic times: "I decided to write [a history, mentioned earlier] from the coming of the savior up to our age, that is, from the apostles, up to the dregs of our time"[1]. Its alternate name, Martyrologium sancti Hieronomi, offers further misleading confidence to its authorship.
Delehaye was of the opinion that the first recension was compiled in northern Italy, probably within the patriarchate of Aquileia, in the 430s or 440s. The 1911 Encyclopaedia Britannica suggested that in its present form it goes back to the end of the 6th century: "It is the result of the combination of a general martyrology of the Eastern Churches, a local martyrology of the Church of Rome, some general martyrologies of Italy and Africa, and a series of local martyrologies of Gaul. The task of critics is to distinguish between its various constituent elements." The Catholic Encyclopedia ("Martyrology") observes that all the surviving manuscripts derive from a lost recension apparently made in Gaul, probably at Auxerre, ca 600, on which the Dictionary of the Middle Ages[2] concurs.
Some of the entries contain brief narratives about the saints which is of historic interest, however the vast majority of entries are nothing but lists of names and places, for example: "On the third day before the Ides of January, at Rome, in the [catacomb] cemetery of Callixtus, on the Appian Way, buried Miltiades, the bishop". The first "historic" martyrologies (containing narrative history of the life of a saint) would not flower until the Carolingian period, starting with the martyrology of Bede.
In its present form the Martyrologium Hieronomianum is a 9th century compilation from various calendars and lists of martyrs, amended and interpolated, the names distorted and multiplied or moved from one date to another according to local cultus. The oldest of the numerous manuscripts is that of Berne. Scholars generally assume that in the lists of martyrs that head each day's entry, newer additions were added at the bottom of the lists, and thus that the first names are most likely to be those from the lost earliest versions of the Martyrologium Hieronymianum.