Waikato Hospital is at "overload" and having to reschedule surgery and turn away non-emergency patients from the hospital's emergency department.
Hospital bosses are blaming the start of winter and influx of patients through the ED who are then being admitted to hospital.
The situation has sparked claims of a "crisis" on social media, with suggestions any patient who does not have a life-threatening injury or disease is now being discharged by the hospital into the care and management of their GP.
"Waikato Hospital is in overload and above capacity which is leading to increased numbers of patients waiting in our ED for an inpatient bed," said clinical director general medicine Dr Douglas Stephenson.
"Because of this situation and for the safety of our patients we are having to reschedule patients for elective surgery that are not cancer or emergency type surgeries.
"Doctors and nurses are doing everything they can to attend to patients care in a timely manner.
"We clearly understand that patients need their surgery done and are doing everything in our power to get their appointments rescheduled as soon as possible."
Stephenson said the hospital would only be taking emergencies at the ED and "anyone who presents at Emergency Department for non-urgent care will likely experience long waits".
Some patients were turning up with non-urgent medical conditions when they should be seeking help from their GP or an accident and medical centre or pharmacy, he said.
"Unless it is a real emergency, please check first with your GP or phone the Healthline (Healthline 0800 611 116) before coming to the Emergency Department at the hospital.
They will give you advice and assessment, and you may avoid a long wait at the hospital while we deal with the more urgent cases."
He stressed that the ED was for serious accidents or urgent medical issues only.
"At the moment the hospital staff are monitoring the situation hour by hour. Waikato Hospital is expecting another influx to come through our ED today. It is working very closely with all the services to make sure beds are freed up as soon as it is safe for patients to go home."