541 patients are waiting on trolleys in hospitals across the country today.
The INMO's latest report shows 392 of them are waiting in emergency departments.
University Hospital Limerick is the most overcrowded with 44 patients in need of a bed.
That is followed by Letterkenny University Hospital and Cork University Hospital on 36.
The INMO is to meet today to discuss its plans for a series of 24-hour strikes.
95% of nurses and midwives voted for industrial action last month in a row over staff shortages and pay.