There was a 12 per cent increase in assaults on prison officers last year.
There were 123 in jails across the country - up from 110 in 2018.
The highest amount was in the Dochas women's prison in Dublin, at 23.
Elsewhere, jails in Roscommon, Laois, Limerick and Cork also recorded high numbers.
Gabriel Keaveny, assistant general secretary of the Prison Officers Association, says some staff suffer serious injuries.
"There's a variation of assaults from dangerous serious assaults on staff," he said.
However, Mr Keaveny said that the figures from March to May of this year show a significant drop.
He says the reworking the prison system around public health guidelines has helped reduce numbers.
"There is an opportunity to radically change how we run the prisons, we cannot continue on an upward trend."
He says the figures are a cause for "serious concern".
"No other workers that we know of faces that level of violence in the work place."
"We expect that we go into work and we go home in the same manner we attended, that's reasonable for any worker."
Meanwhile, a former prison governor claims gangland feuds are leading to an increase in assaults.
Former Mountjoy prison governor John Lonergan says there's a clear reason for the recent trend.
"It's mainly related to gangland feuds carrying on their prison and the whole drug culture," he said.