Medical devices firm Abbott has informed staff in Clonmel that it is seeking 200 redundancies from its permanent workforce.
The company is seeking to achieve the redundancies on a voluntary basis at the vascular manufacturing operations plant.
It is entering into a 30-day consultation period with its employees.
In addition, 39 contractor positions will not be renewed when their contracts expire at the end of March.
The company said the proposed redundancies are part of adjustments being made to "meet the evolving needs of the business and to remain competitive in a challenging global environment".
Abbott's vascular facility in Clonmel currently employs more than 1,400 people.
The company said the facility remains strategically important to its global vascular manufacturing network.
It said the Clonmel site will focus primarily on the manufacture of newer, advanced medical devices.
Capital investment will be made at the site this year to enable it to manufacture these new devices.
Minister for Jobs, Enterprise and Innovation Richard Bruton said that it is a "really tough day" for workers at Abbott in Clonmel, but that the company remains committed to the site.
Mr Bruton said he had spoken to the company and was assured it remains committed to retaining and developing the site, which he said was an award winning one.