Figures from property website Daft.ie show that rents fell by almost 12% over the last year.
Its latest rental report also shows that the number of properties for rent on its website more than doubled to 21,000. The average monthly rent now stands at €885, compared with €1,000 this time last year.
The biggest fall of 15% was in south county Dublin. Rents fell by 10% in Cork and Limerick cities. The report is based on an analysis of rental properties advertised on the website.
Daft.ie economist Ronan Lyons said the figures suggested the average person renting a property could pay €1,600 less in rent this year.