Our Lady's Children's Hospital in Crumlin says it has been forced to introduce visiting restrictions due to a number of cases of the winter vomiting bug.
Visiting is being limited to parents or guardians of children until further notice.
The hospital insists the situation is not serious and the restrictions are a precautionary measure.
There has been a sudden increase in the admission of children from the community who have diarrhoea and vomiting.
Parents are being asked to telephone the hospital before they bring their child to the admissions department.
The hospital says all emergencies will be treated in the normal way.
