The Irish economy would suffer if the UK left the EU, according to a report.
IBEC says a vote to leave would lead to a period of uncertainty.
It is also claiming that trade between the UK and the Republic of Ireland could fall by as much as 20%.
IBEC's Director of EU and International Affairs, Pat Ivory, says we need to monitor the debate closely.
Mr Ivory said: "We need to assess the implications for trade, for investment. We need to monitor how that is going to impact on our exporters as they face the devaluation of sterling.
"We need to ensure that the greatest level of certainty is available to Irish business in their planning and in their investments decisions going forward."