Pharmaceutical and healthcare giant MSD is to close one of its Irish factories with the loss of 280 jobs.
The company is to pull out of its base in Rathdrum, Co Wicklow, by the end of 2015 after a review of its worldwide manufacturing capabilities.
MSD Ireland will continue to employ about 2,000 people.
The Republic's enterprise agency IDA Ireland said it will work intensively with MSD on finding a buyer for the facility and creating alternative employment in the area.
MSD Ireland has sites in Dublin, Carlow, Cork, Tipperary and Wicklow.
Richard Bruton, the Republic's Jobs Minister, on a trade mission in Houston, Texas, said his thoughts are with the workers.
"My first thoughts today are with the workers, their families and all the people of Rathdrum at this uncertain time," he said.
"I have spoken to the company, who employ approximately 2,000 people across several sites, and they have assured me of their commitment to Ireland."
Mr Bruton said the pharmaceutical sector experiences constant change.