There are 516 patients on trolleys or wards today waiting for admission to a hospital bed, according to figures from the Irish Nurses and Midwives Organisation.
The hospital worst affected is University Hospital Galway, with 47 patients waiting.
Other hospitals badly affected are Cork University Hospital with 42 patients waiting and South Tipperary General with 40 patients waiting.
Figures from the INMO show that in September there were 8,101 patients waiting, a 7% increase on the same month last year and the highest number recorded for that month.
It wants the health watchdog, HIQA, to carry out unannounced inspections of all hospitals with high levels of overcrowding and not just the emergency departments.