One in six households in the Republic now shop across the border in Northern Ireland, spending almost €300 per visit.
And retailers have warned 11,000 jobs will be lost in the Republic this year because of the exodus.
Southern shoppers spent €435m in Northern Ireland in the past year a startling new report from the Central Statistics Office reveals.
It's not just alcohol that consumers are stocking up on. Groceries and clothing are even bigger draws, the survey of 15,500 households carried out in the second quarter of 2009 reveals.
Householders spent an average of €286 on their most recent trip across the border with visitors from the midwest, southeast and southwest spending €492 per trip.
Unsurprisingly, people who live near Northern Ireland are most likely to shop here and 41% of households in the border counties do so, with most of them making the journey at least once a month. And 61% of families with children in this area shop in the north.
Some 21% of Dubliners had also made at least one shopping trip north in the 12-month period surveyed, with similar numbers travelling from the midlands.
It's hard-pressed working families who are most likely to be seeking bargains, with twice as many dual-income families going north compared to households where no-one was working.
Almost one in 10 households said they had shopped in Northern Ireland more frequently in the past year than they would have before.