Two more areas, Carlow and Macroom, have been designated Rent Pressure Zones as rents across the country continue to rise.
According to the latest report from the Residential Tenancies Board, the average rent in Dublin is €1,713 - an increase of €114 on the same time last year.
Nationally the average rent, in the period from April to June this year, was €1,202, up from €1,123 a year earlier, representing a 3% increase.
As a result of the rising rents, the Minister for Housing has designated Carlow and Macroom as Rent Pressure Zones, meaning landlords there can only increase rents to 4% annually.
The data is based on actual rents paid on 19,000 tenancies registered with the RTB.
The board's Director Rosalind Carroll said there is no quick fix for the rental sector and regulation is only part of the answer.
She said the average national rent at this point is now 21% higher than the peak at the end of 2007, and the Dublin average is 32% higher.
According to the data, there are now seven counties where the standardised average rent exceeds €1,000 per month - Dublin, Cork, Galway, Kildare, Louth, Meath and Wicklow.