Health service unions have decided not to co-operate with a plan by the HSE to end round-the-clock A&E services at Ennis and Nenagh hospitals.
The unions are also threatening to ballot for industrial action following the collapse of talks on the matter at the Labour Relations Commission.
The HSE is planning to begin withdrawing 24-hour A&E cover in Ennis and Nenagh from Monday.
Unions representing doctors, nurses and administrative workers say the move raises serious health and safety concerns.
Their members will report for duty as normal on Monday, but say they will refuse to co-operate with any changes to work practices.
The unions say they will ballot for industrial action if the HSE does not agree to return to the talks table.