SIPTU is making a urgent call for a meeting with senior management of Roche in Co. Clare.
The future of 240 jobs is unknown tonight after the company announced plans leave the site of its Clarecastle facility near Ennis.
Staff were informed of the news earlier this evening.
SIPTU says the company will begin to wind down its operations in Co. Clare in 2018 or at the beginning of 2019.
The pharmaceutical company operated in the area since 1974.
Sector Organiser with SIPTU Alan O'Leary, says they want to speak with Roche management as soon as possible:
"We're looking for an urgent meeting with the company and we're available in the morning if necessary to meet with the company, to engage with the company.
"But there's going to be an intensive period of a number of weeks I'm sure, as we go through the discussions it will become very clear what's possible, but at the moment, our thoughts are certainly with the workers and their families in terms of a very difficult announcement that I'm sure people are very shocked about."