About 70 Irish tourism businesses are represented at the World Travel Market in London.
They're being joined by Tourism Minister Patrick O'Donovan for the start of Ireland's promotional drive overseas for 2017.
Niall Gibbons, Chief Executive of Tourism Ireland, says there are challenges ahead in what's traditionally been a very strong market, because Brexit has made Ireland significantly more expensive for UK visitors................
Meanwhile, a report published by the Department of Finance and the ESRI is warning that a hard Brexit could reduce growth in the Republic by 3.5% over the following five years.
The report also predicts a higher debt to GDP ratio and an increase in unemployment, with in the region of €12 billion wiped from the value of the Irish economy.