University Hospital Limerick has recorded the highest-ever daily figure of patients waiting on trolleys in any Irish hospital, according to the INMO.
Today's trolley watch figures show that nationally 594 patients are waiting for beds in emergency departments or wards.
In UHL alone a total of 81 patients are without beds - 52 in the emergency department, and 29 in wards.
The union claims a recent ward closure is contributing to the overcrowding problem.
The INMO's Industrial Relations Officer in Limerick, Mary Fogarty, said staff and patients at the hospital are under 'intolerable pressure' today.
She said: "This is the worst-ever figure we've recorded in an Irish hospital.
"This comes less than a week after a 17-bed ward in UHL was shut. The beds that have been closed in UHL need to be reopened immediately.
"We are calling on the Minister to intervene and deal with the chronic overcrowding in the hospital as an urgent matter of patient and staff safety."
The ward has been closed to allow for work on a new fracture unit.
In a petition calling for the ward to be reopened, nurses say they "regularly see over 60 patients" waiting for beds at UHL.
Today's national trolley watch figures show that, after Limerick, the worst impacted hospitals are Cork University Hospital (50 patients waiting for beds) and University Hospital Galway (43 patients).
