The Council of Trade Unions says district health boards may seek to cut services as they try to stretch funds in the coming year.
The Budget increased funding for the boards by $250 million but the CTU says they are still short by about $100 million per year to maintain current services.
CTU economist Bill Rosenberg says this will add to the pressures the boards are already under as they seek to meet growing demand.
He says they could try to bridge the gap by becoming more efficient or by raising productivity.
The senior doctors' union says hospital doctors are already under intense pressure and that will worsen.
DHBs say it's a global issue and the answer lies in continued efforts to work smarter.
The Minister of Health says the sector is in a better position than it was four years ago.