Rents in Connacht rose by almost 8% in the first quarter of this year, according to the latest report from property website Daft.ie
This increase reflects a sharp fall in availability.
In Mayo, rents were on average 8.3% higher than a year ago, with the average listed rent now at €798 per month.
Nationally rents increased by 2% in the first three months of this year.
In Dublin, rents have fallen by 6.5% in the city centre, where the average monthly rent is now €1,974.
In Galway, Cork and Limerick cities, rents are 6% higher than a year ago.
Author of the report Ronan Lyons, an economist at Trinity College, Dublin, says the impact of Covid-19 on Ireland's rental market has sent Dublin and the rest of the country in different directions, as a temporary halt of people moving to the capital city pushed rents down.
Elsewhere, lockdown ground the rental market to a halt, with fewer properties pushing rents up further.