Up to 10,000 SIPTU members working as support staff and chefs in 38 hospitals and health care facilities are set to go on strike.
They have served notice of a 24-hour work stoppage on Thursday, June 20th.
It is over a dispute concerning, what SIPTU says is, the failure to implement pay increases arising from an agreed job evaluation scheme.
The initial action will involve up to 10,000 SIPTU members who provide portering, household and catering services - and those who are employed as health care assistants, maternity care assistants, laboratory aides, chefs and surgical instrument technicians.
John King is SIPTU's deputy general-secretary for the public sector.
He said: "It is time for the Minister for Health, Simon Harris and the Minister for Finance... Paschal Donohoe, to step in and resolve this dispute.
"Failure to do this will undoubtedly bring pressures on the delivery of health services.
"Our members accepted the provisions of all the public service agreements since 2010.
"The Government must now honour its obligations contained within these agreements. It is time to deliver for these workers.
"It is unacceptable that workers should be forced to go into an official dispute in order to get what they are owed."
SIPTU health division organiser, Paul Bell, added: "Members employed in chef grades are also taking action.
"They co-operated with an independent review process of their pay relationship with similar grades in the public health service and in recent weeks have had their hopes of achieving pay justice dashed."
"The ball is now in the court of the Government."
SIPTU members will take strike action in the following hospitals:
- Cork University Hospital
- Cork University Maternity Hospital
- Kerry University Hospital
- Mallow General Hospital
- South Infirmary Hospital Cork
- South Tipperary General Hospital
- Wexford General Hospital
- St Lukes Hospital Carlow/Kilkenny
- Mercy Hospital Cork
- Connolly Hospital Blanchardstown
- National Rehabilitation Hospital
- Beaumont Hospital
- St Ita's Portrane
- Mater Hospital
- St James Hospital
- St Vincent's University Hospital
- Tallaght Hospital
- Our Lady's Hospital Navan
- Louth County Hospital
- Our Lady of Lourdes Hospital Drogheda
- Our Lady's Children's Hospital Crumlin
- Rotunda Hospital
- Central Mental Hospital
- Midland Regional Hospital Mullingar
- Midland Regional Hospital Tullamore
- Midland Regional Hospital Portlaoise
- Naas General Hospital
- Cavan General Hospital
- Letterkenny University Hospital
- Sligo General Hospital
- Roscommon Hospital
- Portiuncula Hospital Ballinasloe
- Galway University Hospital
- Merlin Park
- Mayo University Hospital
- UL Hospital Dooradoyle
- UL Maternity Hospital
- UL Orthopaedic Hospital Croom