One third of women sent to jail in Mountjoy are being freed because the prison is overcrowded.
New figures show almost every female prisoner serving a sentence of less than 20 months has been released early.
In recent weeks Ireland's prison population has exceeded 4,000 for the first time.
More inmates than ever are female and serving long sentences for serious crimes, including murder.
As a result of this pressure on the system, beds for women serving shorter sentences are no longer available.
Figures released by the Department of Justice to Sinn Féin TD Aengus Ó'Snodaigh, show that a third of women at the women's jail in Mountjoy have been released because of overcrowding.
The women are officially on temporary release, but it is unlikely they will be recommitted to the jail, which is still operating 30% over capacity despite the early releases.
