Retail Excellence Ireland has said some of its members are reporting declines in sales of 25-60% as a result of this weekend's ongoing Dublin Bus strike.
The sixth day of industrial action by Dublin Bus workers in a dispute over pay is continuing this afternoon.
Further stoppages are planned for next Tuesday and Wednesday as well as 11 more days of action throughout October.
David Fitzsimons, chief executive of lobby group Retail Excellence Ireland, said: "Retailers are recording sales declines of between 25% and 60% with some retailers considering closing their stores early this afternoon."
"Dublin retailers have had a lot to contend with in recent months including the Luas Cross City construction works and the lack of visitor coach parking facilities in the city.
"When you are talking to large national retail chains who are considering closing their Dublin stores early, you know that the situation is bleak," he said.
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The unions representing Dublin Bus drivers said it is regrettable and unfortunate that businesses have been affected by their strike action.
The NBRU and Siptu are appealing to the business community to use its powerful lobby to appeal to Dublin Bus management, the Minister for Transport and the Department of Transport to try and resolve the dispute.
The unions have called for management to enter talks to discuss workers' demands for a 15% pay increase plus 6% they say is owed since 2008.
Yesterday, Taoiseach Enda Kenny called on both unions and management to engage in talks to try and resolve the dispute.
Dublin Bus has said Nitelink services will not operate tonight or into Sunday morning.
It added that all services, including Airlink and sightseeing tours, will operate as normal from tomorrow morning.