The General Secretary of the INMO, Liam Doran, says patients are suffering in silence in Mullingar Hospital.
Mr Doran, who also said that staff there are overworked, has joined around 30 nurses and midwives at a demonstration at the facility this afternoon to highlight overcrowding and staff shortages.
The protest comes as 30 patients are on hospital trolleys in the emergency department or in full wards in Mullingar.
Speaking to Midlands 103, a nurse, who has worked in the Emergency Department for 15 years, explained what it is like dealing with severe overcrowding.
She said: "You cannot move, health and safety just goes out the window. There are trolleys blocking corridors, blocking fire escape routes and fire hydrants.
"There are people everywhere, you have families standing at the end of a trolley, they don’t even have chairs to sit down beside their loved ones, and they can be there from anything from 24 to 48 hours."