Overall, there was a 14% increase last year.
There was a 14% increase in the amount of serious complaints made by prisoners last year.
The highest number of complaints, since the beginning of 2018, were made in the Midlands Prison.
According to details released under the Freedom of Information Act, there were 70 in 2017 and 80 in 2018.
But since the beginning of 2017, only 16 have been upheld or partly upheld.
Gabriel Keaveny, assistant general-secretary of the Prison Officers Association, says vexatious complaints should be punished:
GardaĆ Searching For Missing Man On Midlands Lake
Enterprise Minister Downplays Government's Ability To Help On Home Heating Oil
Midlands Prison Hit By Mass Overdose Incident
Offaly Man To Complete Marathon Challenge In Honour of Ashling Murphy
Recruitment Of First-Ever Professors For Ireland's Technological Universities Launched
Minister For Rural And Community Development Marks Two Official Openings And Launches In Laois
Offaly Soccer Club Granted Planning Permission For Facility Expansion
Offaly TD Warns Garda Protection For TDs Could Affect Public Access