Nearly all of New Zealand's hospitals are failing to meet the Government's emergency department wait time targets with thousands of patients experiencing delays longer than six hours to be examined.

One patient at Palmerston North Hospital waited more than 48 hours to be examined after arriving at ED, data released under the Official Information Act shows.

Eighteen out of 20 District Health Boards didn't reach the "95 per cent of patients turning up to ED seen within six hours" target between October and December last year, which was the latest data available.

Overall, Capital and Coast had the worst rates in the country with only 64.9 per cent of patients visiting its ED seen within six hours.

The next worse performing DHBs were Palmerston North (73.1 per cent), Hawke's Bay (74.1 per cent), and Counties Manukau (79 per cent).

The only DHBs to achieve the target was West Coast (95.7 per cent) and Tairāwhiti (95.5 per cent).

The data comes after the Herald yesterday reported a "healthy" 50-year-old woman with a brain bleed dying at South Auckland's Middlemore Hospital after allegedly been told by ED staff there would be a eight-hour wait to be examined.

Frustrated she left and returned hours later but it was too late, she died the next day, a doctor working at the hospital told the Herald.

In response, Counties Manukau DHB's acting CEO Dr Pete Watson said yesterday afternoon they had launched an "urgent investigation" into the circumstances of the patient leaving the hospital.

"In the early hours of Wednesday morning a patient presented to our emergency department who then left only to return a few hours later following a life-threatening emergency," Watson said.

"This patient has died in ICU. Our deepest sympathy to the family," he said.

National Party's health spokesman, Shane Reti, today responded saying lessons needed to be learned from any contribution that long waiting times played in the tragic death of a patient at Middlemore Hospital this week.

Reti criticised Labour saying they can't just throw money at the health system and expect results.

"The stressed health system needs real doctors, not spin doctors. ED waiting time targets need to be reinstated immediately, and made readily available.

"New Zealand's overworked health workforce is being let down by a Government that spends excessive amounts of public money yet achieves nothing."

Yesterday, Health Minister Andrew Little said: "The health system has been under serious pressure from years of neglect and underinvestment. It hasn't been working for patients or the health workforce as best as anyone wants it to.

"We're making long-term plans for training, recruitment, retention, and fair pay for the people who care for our families."

The Minister went on to say Labour had taken a number of steps to turn around these years of neglect.

"This includes properly funding the health system and reforming the structures that prevent it from working as well as it could. There is more to do and turning the health system around will take time," Little said.

In relation to the death at Middlemore yesterday, Little said hospital management had advised him that the facts of the case weren't fully known and an investigation was under way to establish them.