There were also 70 assaults by prisoners on staff.
There were 320 assaults in Irish prisons last year.
250 involved prisoners attacking other inmates - with 64 in Cork jail, 44 in Castlerea in Roscommon, and 29 in Midlands Prison in Portlaoise.
Almost four out of every five involved prisoner-on-prisoner attacks.
Eoghan Murphy reports:
There were also 70 assaults by prisoners on staff.
Jim Mitchell, from the Prison Officers Association, says several staff have suffered serious injuries over the years
.