541 patients are waiting on trolleys in hospitals nationwide today, a 39% increase since Friday.
The Irish Nurses & Midwives Organisation's latest report shows 392 of them are waiting in emergency departments.
The figures are the highest recorded so far this year.
University Hospital Limerick is the most overcrowded with 44 patients in need of a bed.
That's followed by Letterkenny University Hospital and Cork University Hospital on 36.
Last week, the HSE warned that it was expecting the numbers of patients visiting emergency departments to rise as a result of the flu.
Ministers Simon Harris and Jim Daly are getting another update from the HSE this morning on the Winter Plan. Flu admissions in hospitals are increasing. INMO says 541 patients are on trolleys. pic.twitter.com/6J7ZkLTaXT
— Shane Beatty (@ShaneBeattyNews) January 7, 2019