Dublin's Mater Hospital says it's under severe pressure today due to high numbers of patients.
After appealing to patients to attend their GPs before attending the facility yesterday - it says it is continuing to experience protracted wait times in the Emergency department today.
Yesterday over 350 people across the country were on hospital trolleys.
The Mater is urging members of the public to only attend its ED in cases of urgent medical need.
"We are asking the public, where possible, to attend their GP in the first instance. Those attending the Emergency Department will be managed according to priority, so less urgent cases will experience delays," the statement reads.