Half of hoteliers in a new survey said the fall in sterling has already had a direct effect on their business - the UK is Ireland's biggest tourism market.
However, despite the risk from Brexit hotel and guesthouse owners are reporting a good start to the year according to the survey by the Irish Hotels Federation.
The survey was taken in advance of the federation's annual conference in the Lyrath Estate Hotel, Kilkenny.
Most of the hotels surveyed said that business levels are up compared to this time last year, while they are also seeing an increase in advance bookings for the year.
The strong growth in business levels from the US also looks set to continue in 2017 with almost half of hotels and guesthouses (48%) reporting an increase from this important market.
Visitor numbers from German and French markets are proving buoyant too, the survey reveals, while 35% of premises are reporting an increase in German visitors so far this year and 18% are benefiting from increased business from France.
Domestic tourism is also proving positive, which the IHF said it especially important for regions outside the main cities and tourism hot spots.
66% of hotels and guesthouses are reporting an increase in business levels from home grown visitors with most also seeing a rise in advance bookings too.
48% of hoteliers said they intend to increase their staffing levels during the year.
Joe Dolan, the president of the IHF, said that the industry is on target to create a further 40,000 jobs by 2021.
Tourism already employs in excess of 220,000 people, making it one of the country's largest indigenous industries.
"There is no doubt that we are seeing a negative impact from Brexit and the sterling differential on 2017 bookings from our key market of Great Britain. This is before any details of what an actual split from the UK will look like and is concerning," Mr Dolan said.
"While we are seeing growth from other EU and long haul markets, that new growth needs to be faster and sustainable if it is to have any real prospect of replacing the value and numbers of our nearest neighbours," he added.
Meanwhile, research carried out by the IHF show that insurance cost Irish hoteliers an average of €730 a room last year.
The total insurance bill for the sector hit €42m last year.
The IHF said what it called "runaway increases" in insurance costs were unsustainable and need to be addressed.
