Hawke's Bay Hospital is at capacity.
People are being urged to seek medical care from their family doctor, medical centre, pharmacy or to call Healthline unless it's an emergency.
Chief Medical and Dental Officer John Gommans said the hospital had been busy for a number of days with patients presenting with a wide variety of illnesses and injuries.
Dr Gommans said people with minor injuries or illnesses, such as colds, could expect to wait for a long time as the Emergency Department prioritised patients needing urgent care.
"Emergency Department clinicians are 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 and urgent treatment."