Ireland welcomed 110,400 fewer overseas visitors in January 2010 than in the same month last year, figures released by the Central Statistics Office show.
The 26 per cent decrease in tourists making visits to Ireland is largely attributable to a decline in the number of trips made by residents of Great Britain.
The number of visitors from Great Britain declined by 65,900 to 142, 400, a drop of 31.6 per cent.
The number of trips to Ireland by residents of European countries declined 29.7 per cent, while the number of visitors from North America fell by 2.2 per cent.
Trips made by residents of Poland and France declined by 7,800 and 7,000 respectively.
Irish residents made 448,900 overseas trips in January 2010, a 10.6 per cent fall on the numbers that travelled in January 2009.
Niall Gibbons, chief executive of Tourism Ireland, said: "We are very much aware that the first quarter of 2010 has been extremely difficult and today's CSO figures for January reflect the impact on Ireland and on tourism businesses across the island".
The extreme/treacherous weather conditions experienced in Great Britain and across mainland Europe at the beginning of the year, which resulted in widespread airport closures and authorities discouraging unnecessary travel, have certainly impacted on visitor numbers, he added.