This dissertation deals with a selection of Latin Lives of Irish saints, most of which belong to the so-called ‘O’Donohue Lives’, which have earlier been dated to no later than the mid-ninth century. The present thesis deals partly with the dates not of that group as a whole, but with several of the individual Lives; a couple of Lives which do not belong to the O’Donohue group have been included as well. Most of the Lives discussed here can indeed be assigned to the eighth or ninth century. The texts have been dated mostly by means of an analysis of the contemporary political interests which are displayed in the Lives; the theories on diffusion of cults put forward by P. Ó Riain have also been of use. In close connexion with the question of date, the composition of a number of the Lives has been analysed, and the result shows that such an analysis is a helpful instrument in the study of the history of those texts. Finally, a study of the use of the nominative absolute in the so-called ‘Dublin collection’ of Hiberno-Latin saints’ Lives has been included.