The National Library of Ireland has a collection of some 1,300 Gaelic Manuscripts, these being manuscripts written wholly or mainly in Irish. All the collection is accessible and over half has been catalogued in depth, the cataloguing being carried out originally by Nessa Ní Shéaghdha and currently by Prof. Pádraig Ó Macháin of the School of Celtic Studies at the Dublin Institute for Advanced Studies. It is being published as Catalogue of Irish Manuscripts in the National Library of Ireland (1967-).

The number of Gaelic manuscripts has grown steadily since the foundation of the Library in 1877. Most of the items have been purchased, the most notable acquisition being in 1931 when 178 volumes were bought from the great library assembled at Cheltenham by Sir Thomas Phillipps. A large number of Gaelic manuscripts have also been donated over the years. For instance, in 1907 the executors of the distinguished Irish scholar David Comyn presented thirty-six items, and in 1944 Séamus Ó Casaide, a noted collector and scholar, presented a total of ninety items. The most notable donation in recent years was An Duanaire Núinseannach (The Nugent Poetry Book), which was presented by Mr John Ronan in 1998.

The manuscripts date from the fourteenth century onwards but many of them include exemplars of earlier texts, some from as early as the eighth century. They represent the Gaelic scribal tradition in most parts of the country but especially in County Cork, north Connaught, north Leinster, southeast Ulster and the cities of Dublin and Belfast. The subject matter includes heroic literature, Ossianic poetry, mythology, religion, grammar, music, astronomy, genealogy, hagiography, legal practice and dinnseanchas (place-lore). The collection includes translations of manuscripts from various overseas traditions, including medical texts from the Arab world. The medical manuscripts (G8, G11-G13, G201, G414, G453, G455, G503 and G512) all date from the fifteenth century onwards and consist largely of Latin texts that were sourced throughout Europe.

The ISOS project will enable scholars to have access to the texts of a number of the Library's more important Gaelic manuscripts without handling the originals, many of which have physically deteriorated over the centuries. While the Library is committed to preserving the collections and has an ongoing programme of conservation, it welcomes the additional protection afforded by the ISOS project. It will also enable the virtual reunion of those manuscripts of which the National Library holds only fragments. The main benefit of the project, however, is that it will assist the Library in fulfilling its remit of making the collections in its care more widely accessible, while simultaneously encouraging and supporting new areas of research.

Gerard Lyne, Keeper of Manuscripts