Ambulance staff have started a 24-hour planned strike as part of an ongoing-trade dispute.
Members of the National Ambulance Service Representative Association (Nasra) have held six stoppages since January as part of a campaign to have their organisation officially recognised by the HSE as a representative body.
They also plan to hold another 24-hour strike in June.
Nasra is a branch of the Psychiatric Nurses Association (PNA).
The HSE does not recognise the PNA or its Nasra branch as a representative body for ambulance personnel.
During previous stoppages, the HSE deployed military ambulances and personnel as well as qualified managers to deal with the shortfall in cover.
Ambulance staff reprsented by Siptu are not involved in the dispute.
