HSE staff are taking industrial action on Friday in frustration over a managerial recruitment freeze.
Trade union Fórsa has organised the work-to-rule action which affects all clerical and administrative staff in the health service.
The union said it was unacceptable these workers were being targeted in a renewed recruitment moratorium.
Fórsa spokesperson Niall Shanahan said they had no option but to down tools.
He told Newstalk radio: “Our members working in the HSE and in Section 38 funded health bodies are taking part in a work-to-rule action, which means that they won't be undertaking tasks, functions or responsibilities associated with any post that's currently vacant.
“This is the action of last resort.”
The HSE’s national director of human resources, Anne Marie Hoey, said the current recruitment freeze is likely to remain in place for the remainder of the year.
“Then once we go into our new service plan for 2024, we have to wait and see what our allocation is within that,” she told RTÉ’s Morning Ireland.
“Any action will undoubtedly have an impact on services. Fórsa notified us on Wednesday evening of the temporary suspension being lifted and the actions that that involve. So the HSE are assessing the impact of that. We have local procedures in place at local and national level to manage that dispute.
“We want to ensure that there is no risk or impact on our patients or critical support services. And if our assessment demonstrates that there is such a risk, then derogations will be sought through our dialogue with Forsa to ensure the protection of services and to ensure that there is no risk to patients, or emergencies through this dispute.
“We will continue to work through the dispute mechanism. But I think it's really important here to mention that we have increased our management, administration staff and indeed all our staff categories in recent years by a significant amount.”
Ms Hoey acknowledged that every action would “undoubtedly have an impact, and that's what we have to assess and we have to work with our local disputes committees to mitigate that risk.”
The HSE remained available to continue discussions in the Workplace Relations Commission, she said.
