New figures show there are 591 admitted patients waiting for a hospital bed.
The Irish Nurses and Midwives Organisation (INMO) says 433 of these are waiting in the emergency department, while 158 are in wards elsewhere in the hospital.
The worst-hit hospitals are University Hospital Limerick (60), Cork University Hospital (55), Letterkenny University Hospital (48) and Sligo University Hospital (45).
INMO members count how many patients are waiting for a bed at 8.00am every morning.
The Trolley Watch counts the number of patients who have been admitted to acute hospitals, but who are waiting for a free bed.
These patients are often being treated on trolleys in corridors.
However the INMO says they may also be on chairs, in waiting rooms or "simply wherever there is space".
