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 job evaluation processes.
It has accused the government of 'refusing to engage'.
The union says that pay adjustments due through 'up-gradings' range from 5% to 7% - mainly applying to health care assistants, maternity care assistants, laboratory aides and surgical instrument technicians.
The union has accused the HSE and the Department of Public Expenditure and Reform of 'sidestepping' their obligations.
Members of the union will now be balloted for strike action next month.
SIPTU 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 on its findings."
Mr Bell added: “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."
He said that around 1,000 chefs employed in the HSE and other related agencies will also be balloted.
According to SIPTU, a review found that the chefs' pay scale was "not appropriate to that of modern skilled craftworker".
Mr Bell claimed moving the workers to existing craft pay scales would be of "small cost" to the health service, but would prove "hugely significant" for its members and for future pay movement.
