An overtime ban involving 6,000 psychiatric nurses will restart from Wednesday.
It's after talks this evening between the Psychiatric Nurses Association and health-service management failed to reach agreement.
Discussions have been taking place to resolve the dispute over the recruitment and retention of staff.
The union says it's disappointed at tonight's outcome, but is left with no other option given the lack of effort from management to resolve the issue.
The HSE says it regrets the breakdown of negotiations with the PNA and remains available to resume discussions.
Peter Hughes, general secretary of the PNA, said: "We suspended our position ten days ago in relation to only working our contracted hours.
"We did that in good faith. We had a clear understanding that the outstanding issues would be resolved. We had engagement with the employer on Wednesday. We were in the WRC today.
"But we are now in a position where from Wednesday onwards, our members will only work contracted hours."
