Hospital support workers have voted overwhelmingly for strike action at 36 facilities across the country.
SIPTU members backed the move by 94%.
The dispute centres on the implementation of a job evaluation scheme.
17,000 workers were ballotted, with the union claiming the government have tried to renege on an agreement over the issue.
Ballot results are in! 🗳️
94% of #ourSIPTU members voted to take strike action in selected hospitals across the country! #ourSIPTU member Anne Sweeney from Letterkenny discusses why we are taking action for #PayJustice pic.twitter.com/X2h4XhmV2F— SIPTU (@SIPTU) May 17, 2019
SIPTU Deputy General Secretary for the Public Sector, John King, said: “The response from our members today is clear and emphatic.
"Our union is demanding meaningful engagement with Government on the resolution to this longstanding issue once and for all. Our members have played by the rules, and kept the health services going in recent times. They deserve to get the pay justice they have waited so patiently for.
“Our members have the full backing of our union on this as it was conceded as part of a previous national public sector agreement,” he added.