Rents nationally rose by 4.5% in the first three months of the year compared to the same period last year, according to new data from the Residential Tenancies Board (RTB) and the Economic and Social Research Institute (ESRI).
The increase was more pronounced outside Dublin, where rental inflation was running at 7% in the quarter.
Inside the capital, the growth was more subdued at 2%.
Increases were recorded in 25 out of 26 counties, the RTB said, with 17 seeing an annual rise of over 5%.
"The Covid-19 pandemic continued to impact the economy and the rental sector in the first quarter of 2021," said Padraig McGoldrick, Interim Director of the RTB.
"Q1 2021 was a period in which the Irish economy experienced a strict lockdown stemming from the spread of Covid-19, which impacted unemployment and had a knock-on effect on the rental sector."
The average rent across the country during the period was €1,320, up €33 from the last three months of 2020.
In Dublin average rent sat at €1,820 a month, up 2% compared to the first three months of last year, with the highest average rent of €2,378 recorded in Stillorgan.
Kilkenny was the county that saw rents rise the fastest during the period at 12.3% when compared to the same period last year.
The lowest monthly rent anywhere in the country was in Leitrim, standing at €596 per month, up 3.8% year on year.
Eight counties - Cork, Dublin, Galway, Kildare, Limerick, Louth, Meath and Wicklow - had average rents above €1,000 per month.
For a typical two-bedroom house, average rent in Dublin at €1,753 was nearly twice what it was outside the capital.
The RTB also said that the number of rental tenancies that were registered with it fell during the quarter to 15,532 from 16,235 in the last three months of 2020, most likely due to public health restrictions.