The needs of acute patients will be met during tomorrow's junior doctor strike, a DHB spokesperson says.

Junior doctors will go on strike tomorrow for 48 hours after talks between their union and District Health Boards (DHBs) broke down last week.

Almost 3000 junior doctors are expected to walk off the job, which will affect all DHBs apart from West Coast District Health Board.

Resident Doctors' Association (RDA) says it wanted a renewed collective employment agreement after the last one expired nearly a year ago.

It says doctors have been forced to take industrial action to keep their existing terms and conditions, which would be changed under the current district health board proposal.

DHBs have previously said the sticking point was over rosters.

DHB national contingency planner Anne Aitcheson told Summer Report rosters had been changed and there would be cover while junior doctors were on strike.

"We are expecting that the acute needs of patients will be met when they present, a lot of the scheduled work has had to be cancelled ... which is outpatient clinics and surgery.

"But for those who have a need for hospital treatment and ongoing care staff will be available."

Emergency departments would be open and staffed tomorrow, she says..

Junior doctors will carry out a second strike at the end of this month.

In 2016 and 2017, thousands of junior doctors took to the streets to protest long working hours and hospital rosters they said were unsafe.

They won a deal to new rosters that cut the number of consecutive days doctors could work from 12 to 10.

However, in November last year a breakaway doctors' union - Specialty Trainees of New Zealand (SToNZ) agreed to a deal with DHBs to work 12 consecutive days if they wish.