A virus has caused the closure of five wards at Huddersfield Royal Infirmary. Hospital officials say 16 patients have contracted the bug, which is thought to be viral gastroenteritis.
Symptoms include diarrhoea, headaches, vomiting and abdominal pain.
No new patients are being admitted to the affected wards in an attempt to control the outbreak.
The hospital trust has said the bug, which is not life-threatening, originated from outside the hospital.
A spokesperson said the decision to close the wards was a "precautionary measure".