University Hospital Galway is one of five hospitals that have experienced their worst-ever overcrowding this September.
New figures show there were 805 patients on trolleys at the Galway hospital over the past month - compared to 21 in September last year - and the Irish Nurses & Midwives Organisation says four nurses at UHG have quit, due to conditions in the hospital's temporary Emergency Department.
The INMO is warning that many hospitals are rapidly returning to the bad old days of overcrowding.
Overall, it's the second worst-ever September on record for overcrowding, with 8,414 people on trolleys at hospitals across the country during this past month.
Today, there are 17 patients on trolleys at University Hospital Galway, 22 at Sligo University Hospital, 12 at Portiuncla Hospital and 7 on trolleys at Mayo University Hospital.