Both prisons in the midlands had more prisoners than space yesterday.
Consistent overcrowding in Irish prisons has sparked calls for more space within the country's institutions.
There are currently over 4,600 people in prison in Ireland, with a total bed count of 4,515, according to data released to Aontú.
The Midlands Prison was full yesterday, and was at 105% capacity, while Portlaoise Prison also had more inmates in the system than there were beds available.
Aontú leader and Meath West TD Peadar Tóibín says the figures show 70% of those currently in prison, have been there before.
He says while the number one objective of prisons is for justice, there is also a rehabilitation aspect: