Hawke's Bay Hospital has reached capacity and, unless it is an emergency, medical staff are urging people to seek care elsewhere.
Acting Chief Medical and Dental Officer, Robin Whyman said the hospital had been busy for a number of days with patients presenting a wide variety of illnesses and injuries.
A hospital spokeswoman said the influx of admissions started on Friday and had continued during the weekend.
"The hospital remains under pressure, so people should not come to ED unless it is an emergency to avoid clogging up the department."
She encouraged people to seek medical care from their family doctor, medical centre, pharmacy or to call the Healthline.
Dr Whyman said emergency department clinicians were highly trained in emergency care, caring for people with life-threatening injuries and illnesses.
"We are asking people to choose well when they are thinking about where to go for care. The emergency department is the place to go for life-threatening, urgent treatment."
He said those with minor injuries or illnesses, such as colds, could expect to wait long periods of time, as the Emergency Department prioritised patients who needed urgent care.
The spokeswoman said the high volume of people admitted all at once happened from time to time and it was not caused by anything in particular.
"There could be more viruses about but there was not just one common illness found, there has been a wide range."
The last time the hospital reached capacity was during the gastro outbreak in August where 5000 Havelock North residents were sick from contaminated water.
Hawke's Bay District Health Board (DHB) chief executive Kevin Snee previously said without the help of the primary sector, the hospital would have been close to a collapse.
On August 15, the DHB reported that from the weekend 60 people had turned up to the hospital's emergency department, 20 patients were treated in hospital, 183 people went to their local doctor and many more were sick in their homes.
In-home care and use of telephone communication meant primary care dealt with the hundreds of patients who would have otherwise stretched the wider system.
The DHB had pioneered the district nurses to work closely with general practice and Mr Snee said he believed that kept more patients at home.
He said: "If we hadn't had that, we would have had many more people coming to hospital and we would have struggled."
Dr Whyman said the pressure on the hospital was expected to remain during the next few days.
The spokeswoman encouraged people not to come to the hospital's ED until the numbers of those admitted decreased so the pressure could be reduced.
She said the Hastings health centre also reported it had been busy during the weekend.
For more information on where to find a family doctor and other health information people could check www.ourhealthhb.nz. The website provided health information specifically for Hawke's Bay people.
Healthline is also available on 0800 611 116 and offered free health advice 24 hours a day.