New data has suggested that 64% of IDA properties are currently unoccupied.
The figures were obtained by Fianna Fáil's spokesperson on business Billy Kelleher.
They show that 98 of the 152 properties owned by the IDA nationwide are laying idle.
There are empty properties across several counties, with concentrations seen in Galway, Cork and Donegal.
Mr Kelleher said: "The majority of these 98 properties are in places outside of Dublin and tend to be located in the parts of the country that are crying out for any degree of Foreign Direct Investment in their community."
"We keep hearing of how this Government intends on spreading regional jobs but the reality on the ground tells us a different story."
He said the situation is unacceptable, in light of the uncertain Brexit landscape.
"This is a substantial number of unused commercial properties that could be the ideal location for an overseas company, big or small, to relocate post-Brexit.
"That potential must be recognised if we have any hope of it being maximised on.
"It's crucial that each of these properties is widely promoted as we face into much uncertainty post Brexit here in Ireland.
"We need to send a clear message that Britain's impending exit from the European Union is not a reflection of Ireland's market or openness to business", he added.