601 people are awaiting hospital treatment on trolleys in emergency departments and wards around the country today.
The INMO says this is the highest figure they've ever recorded in their monitoring of overcrowding.
It comes as nurses at Beaumont hospital prepare to hold a work to rule later this month over the issue, and others get set to ballot on the proposal.
Today's total is up from yesterday's figure of 593.
Lorraine Monaghan is the Industrial Relations Officer for Dublin North with INMO - she says action must be taken now:
The opposition is demanding a statement from the Minister for Health as hospital overcrowding hits a new record.
Fianna Fail's health spokesman Billy Kelleher says Leo Varadkar needs to prove his claim that he's a hands on Minister;
