Update 11.05am There is a record number of patients on trolleys at hospitals across the country - at 656.
The Irish Nurses and Midwives Organisation says the previous highest level of overcrowding was 612 on January 3, last year.
St Luke's Hospital in Kilkenny is the worst affected with 57 people waiting on a bed - followed by University Hospital Limerick on 55.
General Secretary of the INMO Phil Ní Sheaghdha says drastic action is needed.
Earlier: 6% increase in patients waiting on trolleys in 2017
There was a 6% increase in the number of hospital patients waiting on trolleys in 2017.
The Irish Nurses and Midwives Organisation says overcrowding is unlikely to decrease unless drastic action is taken.
Just under 99,000 were recorded as waiting on a hospital bed last year - of that, University Hospital Limerick recorded the highest annual number.
Cork University Hospital recorded figures of 6815 and University Hospital Galway recorded 6563.
The Mater University Hospital was Dublin's most overcrowded hospital with 5238 patients on trolleys during 2017.
Phil Ní Sheaghdha, the newly appointed General Secretary of the INMO has called on the HSE to explain how the predictable increases in Emergency Department admissions remain outside of the scope of hospitals to manage and control.
She said: "Overcrowding in late December and early January is getting worse. Despite investment in winter plans, smaller hospitals are now severely overcrowded which is manifestly unsafe and leads to higher cross infection and poorer outcomes for patients.
"Nursing staff, constantly working in this high pressure, unsafe environment, cannot be expected to put up with this obvious neglect of duty of care to them and the patients they try to care for any longer.
"It appears to me, that staff and patients, on the front line, were abandoned while the system shutdown for Christmas and the New Year.”
- Digital Desk