The Emergency Department at Addenbrooke's Hospital in Cambridge is being severely disrupted by flooding.
It's been caused by a leak from a hot water pipe in the resuscitation and assessment area. No one has been injured.
The hospital says the department is still open but capacity is severely affected and it is diverting some ambulances to other hospitals.
The hospital is currently assessing the damage and starting repairs and has asked patients not to come to the Emergency Department unless they are critically sick or severely injured.
Addenbrooke's is advising people to consider using alternatives such their GP or NHS Direct.