Nurses say that 501 people are awaiting a bed on trolleys and in wards at hospitals around the country today.
The highest number, 52, has been recorded at Our Lady of Lourdes Hospital in Drogheda, Co Louth - 41 of those are on trolleys.
The INMO said that the highest in Dublin is at Beaumont Hospital, where 42 people are on trolleys and five are on wards.
In Cork University Hospital, 27 are on trolleys with four on wards.
At St Lukes Hospital in Kilkenny, 23 are on trolleys with 12 on wards.