Dublin, Galway and Cork are the top three destinations for foreign tourists this Paddy's weekend.
Research carried out by online travel agent Expedia.ie found that holiday bookings to Ireland for St. Patrick’s Day have doubled compared to this time last year.
Americans, Britons, Germans and Canadians are our main visitors.
Jill Lloyd from Expedia said Ireland remained a popular choice for holiday makers at this time of year.
"We've seen a 50% increase in bookings to Ireland for the week of St Patrick's Day compared to the same week last year," she said.
"What's great is that it's not just Dublin they're visiting. It's Cork and Galway too (where) booking are up by over 30%."
Dublin Airport will welcome more than 220,000 passengers over the weekend.
Fifty-five airlines will be flying to more than 170 destinations from Dublin Airport. In keeping with tradition, the airport building is flying the flag and going green.
It is also a big sporting weekend, with thousands returning home from Cheltenham and rugby fans heading to Paris to see whether Ireland can defeat France to win the Six Nations.