Weak sterling is sending Irish consumers online and to the North.
The latest Ibec retail monitor says the exchange rate has continued to make cross-border shopping attractive, while online growth for Irish retailers slowed dramatically, as customers purchased from British-based online retailers instead.
The report also says consumer confidence has dipped significantly over recent months, partly due to Brexit concerns.
Retail Ireland Director Thomas Burke says better value elsewhere has encouraged Irish retailers to make better offers for customers.
"The Irish retailers have reacted strongly to that and have put in place some very good value propositions and have reduced prices to react to that.
"I guess the battle for Irish retailers over the coming months will be to continue to offer consumers the best value for money possible and encourage them to stay here locally and shop locally," Burke said.