West Suffolk Hospital has closed two of its wards to new admissions after patients showed symptoms of the norovirus.
The G4 and G5 wards have closed after nine patients showed symptoms of the highly contagious diarrhoea and vomiting virus.
Both wards at the hospital in Bury St Edmunds remain open to visitors. who have been urged to take extra care to wash their hands with soap and water both on arrival and when leaving the hospital.
Enhanced cleaning in affected areas is now underway to try to stop the spread of virus which usually lasts for two to three days.