All non-emergency inpatient surgeries have been cancelled at Craigavon Area Hospital due to the nororvirus.
The bug, sometimes known as winter vomiting virus, is present all year but becomes more common over winter months.
“Norovirus in the community and is now seriously impacting on our hospitals,” said a trust spokesman.
“We are working hard to arrange new dates as quickly as possible for any of the patients affected.
“The situation will continue to be reviewed to assess if more cancellations are required in the days ahead.”
The Trust are asking people to stay away from their hospitals unless absolutely necessary due to the risk of spreading this infection to our patients and staff.