First-time buyers in parts of Dublin are spending up to 40 percent of their income on their mortgage.
The finding is part of a new ESRI study which looked at the affordability of the national housing market.
It found the average buyer in Wicklow, Kildare and Meath also spend at least 30 percent of their monthly income on their home.
The ESRI says there's a significant urban/rural divide in the figures: