The Council of Trade Unions says the health system is $150 million short of the funds in the Budget that it needs to meet demand.
The Government says public health services have got the biggest increase in funding in the Budget, but CTU economist Bill Rosenberg says it's not enough to maintain current services.
"The health budget is increasing by around $300 million for the operational part of it," he says. "That's about $150 million short of what's required just to meet increased costs and increasing population and ageing of our population."
In the Budget delivered to Parliament by Finance Minister Bill English on Thursday, total spending on health goes up to $14.7 billion a year, including $1.6 billion over four years to improve frontline health services.
Mr Rosenberg says he estimates district health boards have $50 million less than they need.