The latest Daft.ie report shows nationwide rents in Quarter two were up by an average of 7 per cent on last year.
Prices in Limerick jumped by 21 per cent in the past year - while Cork, Galway and Waterford all recorded increases of over 10 per cent.
At the start of this month, only 151 homes were available to rent across those four cities combined.
Trinity College Economist and author of the report Ronan Lyon says it's impacting on students' college choices.
College students are feeling the pressure, with another report in the Irish Independent suggesting students are paying 8,000 euro for accommodation for the year.
A survey, which reviewed on-campus and private student housing across 15 institutions and nine counties, found that twin shared rooms often cost more per person than single or en suite options.
The highest price was at the Royal College of Surgeons in Dublin, where a shared twin room at Millin House costs €8,800 per student, bringing in €17,600 per room for the college annually.
