Hospital Emergency Departments could be facing further disruption in the new year - by support staff.
SIPTU is balloting over 25,000 members for strike action at the country's main hospitals.
The Union says it is over a failure by the HSE to implement parts of the public sector pay agreements in the past - rather than future pay demands.
Nurses have already voted for industrial action over working conditions.
SIPTU's Paul Bell says they'll ballot porters, catering staff and others working in ED's; "Some of our professional colleagues who provide certain services, diagnostics and so forth, they may also become involved because they have become impacted on by the behaviour of the Heath Service Executive.
"But we want to assure the public that we have wanted to resolve these issues for the past 15 months and the Work Place Relations has been involved in one or two of them."