A record high number of people are on a trolley or ward waiting for a hospital bed.
The INMO says 714 people are waiting for a bed at hospitals around the country.
Of these, 513 are on trolleys and 201 are on wards.
The total is higher than a previous high of 677, set in January.
University Hospital Limerick has the most people waiting on trolleys, at 80.
This is followed by University Hospital Galway (45), Cork University Hospital (43), Tallaght Hospital (40), Midland Regional Hospital, Tullamore (37) and Midland Regional Hospital, Mullingar (31).
The hospital with most people waiting on a ward is also University Hospital Limerick, at 25.
Fianna Fáil health spokesperson Billy Kelleher has described the figures as "absolutely deplorable".
He said: "Last week was the worst week ever experienced for emergency department overcrowding. Today we are seeing the worst day ever.
"It's truly shocking.
"Not only are the figures themselves completely unacceptable, but the length of time that patients are being kept on trolleys is extremely worrying.
"I have heard reports of a 64-year-old man having spent 109 hours on a trolley in Tallaght Hospital - that's over four and a half days.
"This is surely some breach of human rights?".
He added: The Minister for Health and the HSE have completely failed people this winter.
"It is now the middle of March and the situation is actually getting worse."