BASSETLAW Hospital has closed one ward to new patients because of an outbreak of the winter vomiting Norovirus.
A bay in one ward at Doncaster Royal Infirmary is also closed.
Staff are asking visitors to stay away and not risk bringing infections into hospital.
The advice is to not go to hospital as an inpatient, outpatient, or visitor if you have any signs of a stomach upset.
If visiting someone in hospital is unavoidable, wash your hands before and after the visit. Use the hand gel provided at the entrances to the wards and wait until you have been free of symptoms for at least 48 hours before visiting hospital.
The first sign of Norovirus is usually a sudden sick feeling followed by forceful vomiting and diarrhoea.