The winter vomiting bug norovirus is now causing problems at three hospitals in Cornwall.
The worst affected is the Royal Cornwall Hospital in Truro where several wards have been closed and some patients moved to other hospitals.
One ward has been closed at the West Cornwall Hospital in Penzance and St Michael's Hospital in Hayle has also been affected.
Visitors are asked to stay away unless it is for a critically ill patient.
Health chiefs have said they will review the timetable on Monday for non-urgent surgery to ease the pressure on services.
The symptoms of the norovirus infection include a sudden onset of nausea, followed by vomiting and diarrhoea.
Norovirus is contagious from the moment a person begins to feel unwell until at least three days after symptoms have stopped.