Hawke's Bay hospital is at capacity and people with non-urgent conditions should seek treatment elsewhere.
The hospital's emergency department is giving priority to patients who need urgent care and the District Health Board said people with minor injuries or illnesses are in for a long wait.
It said the unexpected rise in patients was not related to the earthquake, and the pressure on services would probably last until the weekend.
People with non-urgent conditions should go to their family doctor or medical centre, call a pharmacy, or seek advice from Healthline.