The number of jobs advertised in the State dropped last month, according to new figures from the Economic and Social Research Institute.
There were fewer vacancies in the services, construction, and retail sectors, with jobs across all areas decreasing from 22 per cent to 16 per cent, according to economists.
But the ESRI warned overall figures showed no significant drop in the economy.
"In April there was a really large increase in vacancies in the economy so this month is a fall back on that with things returning back to normal," said researcher Nicola Doyle.
"Looking at vacancies over the last year there has been an increasing trend and that trend is still positive."
The Fás/ERSI Employment and Vacancies Survey found positions in the industrial sector remained stable, with 23 per cent of firms indicating they had jobs.
The survey also revealed employment prospects look stable for the next few months, with bosses anticipating no change in employment levels in the near future.
The most difficult to fill vacancies in each sector in May were: construction - quantity surveyors and site managers; industry - engineers, sales staff and managers; retail - sales staff; and services - chefs and engineers.