Patients were waiting an average of more than 11 hours to access emergency departments last month, new figures show.
HSE statistics released to Sinn Féin health spokesman David Cullinane show Mercy University Hospital in Cork had the highest average wait time in the country, at 21.6 hours.
Cork University Hospital was the second highest, with average wait times of 19.6 hours.
Patients had to wait an average of 18.4 hours for access to the emergency department in Tallaght University Hospital, and 16.8 hours in St Vincent's University Hospital.
Waiting times were longer for people aged over 75 than under 75.
Mr Cullinane said hospitals across the country were under “severe pressure” due to overcrowding.
“Major hospitals across the State remain under severe pressure from emergency department overcrowding. They do not have the capacity to handle the patients that are coming their way,” he said.