Rents nationally rose by an average of 13.5 % in the year to the end of December, according to the latest quarterly rental report from property website Daft.ie.
This is the largest annual increase in rents ever recorded in the Daft report, which extends back to 2002.
In Mayo, rents were on average over 7% higher in the last quarter of 2016 than a year previously.
The average advertised rent in Co Mayo is now 593 euro – up 14% from its lowest point.
Rents in Galway are now 10% higher than a year ago- averaging 975 euro per month, while in Dublin, rents increased by 14.5% last year to an average of 1,643.
Author of the report, TCD economist Ronan Lyons says these latest figures are very concerning.
While measures to control rent inflation may help sitting tenants, he says they do little to address the underlying issue of a lack of supply.
He says addressing construction costs remains the best way of addressing supply shortages.