240 jobs are to go at Roche Pharmaceutical in County Clare.
The company says it will close its operations in Clarecastle by the end of 2018.
Roche had announced last November that it was attempting to transfer the plant to a global pharma services company, but today it says those negotiations have ended unsuccessfully.
Staff are being notified of the decision this evening.
Local Fine Gael TD Pat Breen says his thoughts are with the workers and their families: