The Waikato District Health Board says Waikato Hospital is overloaded with patients and extra staff have been called in to ease the situation.
A hospital spokesperson, Jo-Anne Deane says the 600-bed hospital has been running at 98 to 101% occupancy all week.
She says extra staff were called in on Sunday to assess patients.
Non-urgent patients were asked to consider seeing alternative medical providers or returning in the morning.
Ms Deane says patients should visit the emergency department only in the case of a real emergency.