The number of homes available to rent has reached its lowest level since 2006.
According to the latest quarterly rental report from Daft.ie just 2,700 homes were available to rent nationwide on 1 May this year.
The shortage of supply has pushed up average rents across the country to €1,366 a month - up over 8% year-on-year.
While the increase in Dublin was less than 7%, in Cork, Galway, Limerick and Waterford rents increased by 10% to 15% over the last year.
Rents have increased by an average of 12% in Munster, Connacht and Ulster.
Average monthly rent in Dublin is at €2,002 and €968 in the rest of the country.
The average listed rent is now €337 higher per month than the previous peak in 2008 and almost €625 higher than the low seen in late 2011.
Responding to the report, the Simon communities said the figures highlight the inability of the private rental sector to provide adequate and secure housing for all.
The report's author, Professor of Economics at Trinity College Ronan Lyons, said the country needs more rental supply and rent pressure zones are not working because of that lack of supply.
Speaking on RTÉ's Morning Ireland, Mr Lyons said: "The solution is a relatively straightforward one, at least to say, is that we need more rental supply. The challenge is of course doing it."
He said the rent pressure zone legislation is supposed to cover both sitting tenants and new tenants.
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But Mr Lyons said it is impossible for new tenants to police the landlord and know the 4% increase a previous tenant might have faced when they are entering a market with no supply.
"Rent pressure zones are not working for precisely the reason they were introduced, there's a lack of supply.
"It's a bit like, sort of, cutting off your thermometer to say that the temperature hasn't gone up as much. Rents are the signal, not the problem. The problem is a lack of supply."
According to the report, average rents across the country in the first quarter of the year with year-on-year change, are as follows:
Dublin: €2,002, up 6.8%
Cork: €1,331, up 10.0%
Galway: €1,260, up 11.4%
Limerick: €1,195, up 14.4%
Waterford: €986, up 13.6%
Rest of the country: €968, up 9.7%
Minister for Housing Eoghan Murphy said the rise in the cost of renting was the slowest in six years.
Speaking on RTÉ's News at One, Mr Murphy said: "Rents remain unacceptably high, but rents are rising at a rate that we haven't seen since 2013. A very slow rate."
The minister added that new rules which will weaken landlords' powers of eviction will be signed into law within the next fortnight.
Large, institutional landlords will be covered by the legislation so "tenants renting from those properties have the same protections as tenants renting from traditional landlords," the Mr Murphy said.
"We know we need to do more. That's why protection for renters is so important."
Responding to the report, Threshold - the national housing charity - said rent increases shown in this latest report "reinforce our concern about the inadequacy of the Housing Assistance Payment as a means of supporting those seeking increasingly expensive and scarce rental accommodation".
The Simon Communities of Ireland said that the figures highlight "the inability of the private rental sector, in its current form, to provide adequate and secure housing for all".