There are 345 patients on trolleys or on wards awaiting admission to a hospital bed on Wednesday, figures show.
The Irish Nurses and Midwives Organisation (INMO) said there were 296 patients waiting in the emergency department, while 49 were in wards elsewhere in hospitals.
There were 48 patients deemed by doctors to require admission waiting for a bed at Cork University Hospital.
The INMO figures also show there were 36 patients on trolleys or on wards at University Hospital Limerick and 34 at Sligo University Hospital.
Nurses said there were no children waiting on trolleys for admission to a bed at the National Children's Hospital in Tallaght, Temple Street hospital or Our Lady's hospital in Crumlin.
"The INMO has repeatedly warned of rising trolley figures over the past several months. Our members are exhausted after the recurrent waves of Covid-19, and they cannot withstand a return to the overcrowding crisis of the past," David Hughes, INMO deputy general secretary, said.
“At a time when distancing is essential to maintain infection control, lining corridors with trolleys poses huge risks to patient and staff safety.”
On August 10th, the INMO recorded 385 patients on trolleys, the highest figure since the onset of Covid-19 in March 2020.
Mr Hughes said the INMO had previously called for “zero tolerance of overcrowding in Irish hospitals” and the organisation was “seeking urgent action from the HSE on scaling back services in badly hit hospitals, taking on extra capacity from private hospitals, and supporting GPs to return to their normal clinical work to keep hospital environments functioning and safe”.
Dr Mick Molloy, a member of the Irish Medical Organisation (IMO) consultant committee, said the number of people on trolleys was "completely unacceptable" and had become a "year-round problem".
“When I started my career, this was a winter problem but now it’s a problem 12 months of the year. We’ve known there’s a capacity issue for decades. There is also an issue with the staffing of our services,” he said.
Across medical services, Ireland had "among the lowest ratio of working staff to patients that exists in a first world country".
The high number of patients waiting on beds on Wednesday was “indicative of the low number of beds in Ireland”.
“Numbers of 20-40 patients waiting on beds are ridiculous and should never be allowed to happen. Unless the Government is willing to invest significantly across the country, this is going to continue to be a year-round problem,” Dr Molloy said.
Dr Eamonn Brazil, an accident and emergency consultant at Dublin's Mater hospital, where 16 patients are awaiting admission to a bed, said the hospital was "in okay shape at the moment. Part of that is because we increased our space by 50 per cent and have some extra staff we managed to keep on, so we're more efficient".
He added: “There are more people coming in to us but the numbers waiting on beds are okay at the moment, or better than last year.”