Business in the city centre was not adversely affected on the first day of the bus strike on Sunday, but it declined yesterday.
That's according to the Dublin City Business Improvement District, or BID, which represents 2,500 businesses in the city.
It reported footfall in the city centre, as recorded by its counting cameras, as steady on Sunday, the first day of the strike.
However, it subsequently declined by 15% yesterday.
Dublin BID members have been reporting a decrease in trade in line with the footfall figures.
The average business is seeing a decline in business levels of between 15 and 20%, according to the group.
"We urge all parties to engage in meaningful negations through the Labour Relations Commission to come to an agreement. City centre businesses are simply not in a position to sustain declines of this magnitude," Richard Guiney, CEO of Dublin City BID said.
The Small Firms Association says losses of the order of about €4 million could be realised by businesses in the city.
It says the losses will arise from lost productivity and consumers simply staying away from the city.
"While employees are making great efforts in attending work, there is still time lost and the overall cost in terms of days lost is difficult to access, but the SFA estimate if employees in Dublin lost just 30 minutes today the result is 53,431 days lost, a lost productivity cost of just over €4 million," Avine McNally, Director of the SFA said.