The public are being warned to expect long wait times at the Emergency Department at UHG.
Pressure over the weekend is still being felt, and some procedures are being cancelled.
Over the weekend, close to 400 patients passed through the ED, with a further 273 attending yesterday.
Due to the resulting pressure, UHG is postponing some elective procedures and prioritising urgent, time sensitive cases.
As of this morning, there are around 50 patients waiting on trolleys.
The public are reminded that the Emergency Department should only be used in genuine emergencies, and GPs or out-of-hours services should be used otherwise.
The Roscommon Injury Unit is also open from 8am to 8pm and can treat a range of injuries for both adults and children over five.