New figures from the gardai show that more people have been killed on the road so far this year in Donegal and Limerick than in any other counties.
The figures also reveal that most Irish road deaths involve single-vehicle crashes in the early hours of the morning.
Of the 90 fatalities since the start of the year 59 were mainly young people in cars that either overturned or crashed without colliding with another vehicle.
The highest number of victims were in Donegal (8), Limerick (8) and Wexford (7).
Assistant Garda Commissioner Kevin Ludlow, head of the Garda Traffic Corps, said the three counties were particular areas of concern.
He added it was generally recognised that speed was a factor in one-third of all fatal accidents.
Senior gardai have found that many of the single-vehicle collisions involved cars overturning on sharp bends on rural roads and ending up on banks.
Of the 90 people killed up to the start of this month, 43 were drivers, 24 pedestrians, 16 passengers, six motorcyclists and one pillion passenger. This is a drop of 18 on the same period last year.
There were 84 collisions -- 14 fewer than in the first five months of 2009.