Bosses at Macclesfield Hospital accident and emergency unit are urging only those with genuine emergencies to attend as a rush of patients has caused long delays.
Waiting times at A&E are currently around five hours after a large number of ill patients arrived at the emergency department this morning.
Now East Cheshire NHS Trust, which runs the hospital, is asking those considering a visit whether they require emergency treatment.
A spokeswoman said: "If you are unwell please think about whether you really need A&E services.
"Remember you can get medical help at your local pharmacy, through NHS Direct on 0845 4647 or through your GP before visiting A&E."