THE new drink-driving limit will come into effect from midnight tonight, ahead of the bank holiday weekend.
The new legislation will reduce the current maximum blood-alcohol level from 80mg of blood to 50mg in most cases.
This means that most people will not be able to drive after having a single pint.
Certain categories of drivers will have to comply to a tougher restriction of 20mg, including professional drivers and motorists driving for less than two years.
Road safety is of particular concern during bank holiday weekends because of the increased likelihood of risky behaviour.
Minister for Transport Leo Varadkar said that the new limit would encourage people not to drink at all if they are to drive later in the day.
"On the October bank weekend last year 11 people lost their lives," he said. "I don't want to see anyone lose their lives this weekend."