Irish authors are in high demand, as new library figures show 11 of the 20 of the most popular adult books are by Irish writers.
Eighteen of the most borrowed books were children's titles, with Roderick Hunt proving the most popular author.
Jeff Kinney's 'Diary of a Wimpy Kid: Double Down' was the most popular book.
The two books not aimed at children that made the list were 'Eleanor Oliphant is Completely Fine' by Gail Honeyman and 'Skin Deep' by Irish author Liz Nugent.
When books aimed at adults are separated out, James Patterson retains his popularity with Irish readers - and tops the list of the 20 most popular authors.
While 'Eleanor Oliphant is Completely Fine' was the most borrowed adult title in 2019.
Michelle Obama's 'Becoming' topped the charts in both eBooks and eAudiobooks.
The top four adult books borrowed are by women authors, and the lists show books by women are very popular with library members.
The top 20 lists for most borrowed adult books, eBooks and audiobooks are dominated by women - with 12 female authors included in each.
The figures have been released ahead of National Library Open Day this Saturday, February 29th.
Library staff will be on hand to show visitors around, demonstrate online services, and sign them up for a library card if they do not already have one.
Tom Enright is chair of the National Libraries Development Committee.
"Whether you want to borrow books, use the internet, make use of digital equipment, enjoy the community space and wide range of activities, or you would prefer to download an audiobook, eBook, or online newspaper to your device, it is all available to you completely free with your library membership.
"Come along on Saturday, February 29th to find out how to make the most of your library."