The union representing care staff at the Central Mental Hospital in Dublin has said it is hoping to reach agreement with the HSE before instituting industrial action next month.
Care officers and nurses at the unit have voted in favour of industrial action.
The SIPTU members have taken the action after HSE management said it plans to change the terms and conditions of its staff.
The staff said this is in breach of the terms of the Croke Park agreement and they will now undertake industrial action.
Louise O’Reilly, SIPTU's sector organiser, has said the strike committee will decide on whether its members will work to rule, or take strike action.