Auckland public hospitals are short of more than 120 registered nurses, a New Zealand Nurses Organisation survey has shown.
The survey of NZNO members working at Auckland District Health Board showed a shortage of 48 registered nurse positions at Starship Children's Hospital alone.
NZNO organiser Craig Muir said the shortages were shocking.
"NZNO members have been telling us how overworked they are but we had no idea how bad it was," Muir said.
He said running a DHB 120 nurses short was dangerous.
"It's dangerous for overworked, stressed staff and the flow on effect of that is concern for patient care."
Muir said the DHB was trying to save $4 million but leaving 120 positions unfilled was not the way to do it.
"All New Zealanders ought to be able to rely on the best possible care when they are in hospital. It's hard to see how that can happen when wards are so short staffed.
"Overwork and burn out inevitably lead to lower standards of care. It is only a matter of time before a serious incident occurs."
Muir said the situation could easily be resolved if the DHB prioritised staffing levels and patient care,
"DHBs and unions need to draw a line in the sand - cost cutting should not impact on staffing and quality patient care."
The Auckland DHB refused to confirm or deny there was a nurse shortage at Auckland hospitals.
Acting chief executive Dr Margaret Wilsher said in a statement that in March and April there were at least five more nurses on deck at Starship Hospital than at the same time last year.
She said recently there had been approval to recruit another 28 nurses for Starship.
Wilsher said nursing levels were reviewed three times a day to ensure there were the right number of nurses to provide care on the wards.