More than 7,000 hospital support staff are to be balloted for strike action.
SIPTU has announced the move as part of an ongoing dispute concerning pay awards granted under agreed job evaluation processes.
The union has accused the HSE and the Department of Public Expenditure and Reform of side-stepping their obligations.
The union's Health Division Organiser, Paul Bell, said: “It is disappointing and regrettable that the Government made a decision to frustrate a process which it freely entered into under the Lansdowne Road Agreement in 2015. It has frustrated the agreed job evaluation process and refused to engage in its findings.
“The process has categorically confirmed that our members have been underpaid for many years and going forward should be entitled to migrate to pay scales which recognise their contribution to the provision of essential health services throughout the country.
“Pay adjustments due through up-gradings range from 5% to 7% and mainly apply to Health Care Assistants, Maternity Care Assistants, Laboratory Aides and Surgical Instrument Technicians. It is understood that monies are due to these workers since September and October 2018, the dates on which Phase 1 and 2 of the Support Staff Job Evaluation process was completed.
Mr Bell said that the implementation of pay upgrades should be applied within eight weeks of the evaluation.
He said: "Despite the determined efforts of SIPTU representatives to engage on this matter the HSE and the Department of Public Expenditure and Reform have sidestepped their obligations.
“Approximately 1,000 chefs employed in the HSE and related agencies will also be balloted for strike action. These workers had their roles reviewed and it was determined that their pay scale was not appropriate to that of a modern skilled craftworker. In a jobs market where it is extremely difficult to hire and retain chefs, an independent review identified that chefs have no pay relationship with any of the craft groups within the public service and should be permitted to migrate to the existing craft pay scales.
“This migration, while of a small cost to the health service, is hugely significant for our members and in particular for future pay movement. Until recent months, we also understood that the Department of Health and HSE had agreed to cooperate with and implement these changes. They have failed to do this and our members feel badly let down and want to take action.”
