Norovirus affects two wards at Wrexham Maelor Hospital
One ward at Wrexham Maelor Hospital remains closed to admissions and another is partially affected due to an outbreak of diarrhoea and vomiting.
Three wards were initially closed on 20 December due to a high number of cases involving the norovirus bug.
People with symptoms who are due to attend an appointment or for admission should telephone ahead first.
The health board advised people who have had symptoms over the last 48 hours not to visit others at hospital.