Around 3000 junior doctors begin a 48-hour strike this morning after talks between their union and district health boards broke down.
The doctors are on strike from 7am today until 7am on Thursday.
The New Zealand Resident Doctors Association says DHBs are trying to take hard-won terms and conditions out of doctors' contracts.
"At the moment if a resident moves to another employment it's by agreement. Under what they're claiming, they want to send people anywhere and if they don't go, they could loose their jobs," Dr Deborah Powell of the association said.
Dr Powell says the DHBs are also seeking to take the union out of the contract.
She says the resident doctors want the association to act on their behalf, but the employers would prefer the flexibility of talking directly to them.
"It was only a couple of years ago that we had to strike to get safer hours of work. Those provisions the employers are trying to claw back as well."
DHBs say anyone needing treatment for minor illnesses over the next two days should go to a GP.
But if you're suffering from a sudden or serious illness you should definitely still go to hospital.
The resident doctors have also voted for a second 48-hour strike on January 29.
Meanwhile nurses have thrown their support behind the junior doctors in the dispute.
The New Zealand Nurses Organisation warns unsafe working conditions imposed on resident doctors would impact on the quality of health care in New Zealand.
NZNO Industrial Advisor Lesley Harry says nurses can testify that what doctors are saying about short staffing and burnout is a fact.
She says NZNO members in hospitals increasingly report situations where staffing levels and working hours mean patients are not receiving the standards of care they should expect.