An extra 37,500 visitors from North America helped bolster a 5.5% increase in tourism in the first three months, while British visitors bucked the recent trend by increasing their numbers.
CSO figures showed overseas arrivals increased by 5.5% in the first quarter of 2019, around 106,100 more when compared with January to March 2018.
US and Canadian arrivals increased by almost 11%, while British visitors increased by almost 1.5%.
Visitors from continental Europe continue to grow, with an increase of 7.6% being led by a spike in French and Spanish tourists.
There was also a rise in numbers from Australia and other so-called "emerging markets", growing almost 7% year on year for the first three months of 2019.
Tourism Ireland chief executive Niall Gibbons cautioned that while growth was positive, there were signs to be wary.
"It is early days yet – arrivals for the first quarter represent around 18% of total annual arrivals and growth in the month of March alone has slowed to 3.3%," he said.
He said the British increase was encouraging but tourism could not become complacent in the wake of Brexit.
"While we welcome the fact that arrivals from Britain are up 1.4%, we know that the Brexit extension will continue to cause uncertainty for the summer season.
"However, we will continue to monitor the British market closely, working in conjunction with our British-based Brexit Taskforce," he said.
For March alone, trips by British visitors decreased by 3.1% to 284,300, the CSO said.
The total number of overseas trips made by Irish residents during March increased by 13.5% to 634,000, it said.