INMO's Liam Doran says the situation is "totally unacceptable" and requires "emergency action"
541 people are on trolleys at hospitals across the country, according to the Irish Nurses and Midwives Organisation (INMO).
The university hospitals in Cork and Galway are the worst affected - with 48 people waiting for admission to beds.
The INMO says the situation has disimproved since December 2015.
On this day last year, there were 331 people on trolleys in emergency departments or wards.
The organisation is calling on the HSE to introduce an emergency nurse staffing initiative to address the matter.
INMO General Secretary Liam Doran said: “Today’s figure, in the context of the bed closures and the comparison with this time last year, must be viewed by everyone as totally unacceptable and requiring emergency action.
"The INMO is calling for the measures specified as immediate actions necessary, recognising the capacity limitations that exist at this time, to minimise overcrowding and, as far as possible, the compromising of care to patients and to protect the health and safety of staff.”