Book of Leinster

Book of Leinster
Dublin, TCD, MS 1339 (olim MS H 2.18)
f. 53
Also known asLebor Laignech (Modern Irish Leabhar Laighneach); Lebor na Nuachongbála
TypeMiscellany
Date12th century, second half
Place of originTerryglass (County Tipperary) and possibly Oughaval or Clonenagh (County Laois)
Language(s)Old Irish, Middle Irish
Scribe(s)Áed Ua Crimthainn
Sizec. 13″ × 9″; 187 leaves
Condition45 leaves lost, according to manuscript note.
Previously keptBy the Ó Mhorda and Sir James Ware
Terryglass
Location of Terryglass (Tír Dhá Ghlas) in Ireland

The Book of Leinster (Middle Irish: Lebor Laignech Middle Irish pronunciation: [ˈl͈ʲevər ˈlaɣʲnʲəx], LL) is a medieval Irish manuscript compiled c.1160 and now kept in Trinity College Dublin. It was formerly known as the Lebor na Nuachongbála ("Book of Nuachongbáil"), a monastic site known today as Oughaval.

In 2023, Trinity College started an extensive restoration project to make the manuscript available for public viewing.

Fragments of the book, such as the Martyrology of Tallaght, are in the collection of University College Dublin.