The Mater Hospital is advising people that its Emergency Department is very busy at the moment.
Management say they've admitted a lot of seriously ill patients recently, many of whom are still waiting for a bed.
The hospital is suggesting those with less serious injuries to go to their GP or another clinic for treatment.
In a statement, the hospital said it is "committed to treating everyone who presents at our ED, but we do so strictly in order of medical priority".
It is asking people to think about "all their care and treatment options", and "the length of time you may be waiting in ED".
It has suggested those with less serious injuries attend its Rapid Injury Clinic in Smithfield.
There, patients can get treatment for injuries including sprains and strains, broken bones and minor burns, bites and eye injuries.