The number of patients on hospital trolleys across the country has increased significantly this week, compared to last week.
Today, there are 565 patients waiting for a bed - with 583 on trolleys yesterday and 565 on Monday.
Last week's trolley figures were between 300 and 400.
The INMO figures show Galway University Hospital is the third most-overcrowded today with 44 patients on trolleys, while there are 22 waiting for a bed at Sligo University Hospital and 13 at Mayo University Hospital.
The ongoing overcrowding and the pressure this is putting on nursing staff are among the reasons INMO members are taking strike action later this month.
Nurses will go on a 24-hour strike on Wednesday 30th January - three weeks from today - with 5 further days of strike action planned for February.
The union says members are fed up dealing with low pay and poor working conditions.
However, the Irish Patients Association says patients lives are at risk if the proposed strike by nurses goes ahead at the end of the month.