Rent for new tenancies outside Dublin increased 12 per cent to 1,280 euro a month.
The cost of rent outside Dublin is rising twice as fast as in the capital.
Latest figures from the RTB for the end of last year, show average rent for a new tenant in Dublin was almost 2,100 a month, an increase of 6 per cent on the previous year.
Rent for new tenancies outside Dublin increased 12 per cent to 1,280 euro a month.
In Maynooth, average monthly rents are €1,627, while in Naas the monthly cost is €1,527.
In Newbridge, the figure is €1,250 and in Baltinglassit costs an average of €1,199 per month.
Just under 56,500 new tenancies were registered with the RTB last year, a fall of 21 per cent on the previous year.
Research Officer with the ESRI, Rachel Slaymaker, says those who live in the capital are slightly better off.