Senior doctors and dentists working in hospitals are holding a two-hour strike over deadlocked pay negotiations between their union and Te Whatu Ora.
About 250 planned care procedures would be impacted, Te Whatu Ora said, but it had contingencies in place and emergency departments would be open.
The health agency said it had put a fair deal on the table, but the Association of Salaried Medical Specialists argued increase on offer of $15,000 to $26,000 failed to keep up with inflation.
More than 100 senior doctors and dentists gathered along Christchurch's Riccarton Ave, opposite the city's hospital.
Several demonstrators held up placards and were sporting red 'Invest in our Health' t-shirts, with a number of motorists honking in support.
Association of Salaried Medical Specialists president Julian Vyas said the strikes were about meaningful change.
"This has been portrayed by Te Whatu Ora as doctors simply wanting to line their pockets, and that's not the case. We want our pay to keep pace with inflation. We also want to start a change - to draw a line in the sand of the erosion of the public health system."
Vyas said he expected more medical specialists to move overseas if changes were not made.
Anaesthetist Dr Dick Ongley called for a system where public servants did not have to resort to industrial action to achieve a pay rise.
"We would love the public health system to become healthier and we want to fight for that.
"We call tell that things aren't going in the right direction."
Association of Salaried Medical Specialists executive director Sarah Dalton said on Monday Te Whatu Ora have included regular salary-step increments members would get irrespective of whether they were bargaining on those numbers.
"So we would say they have inflated those numbers beyond what's actually on the table."
But Te Whatu Ora chief people officer Andrew Slater told Morning Report the current offer was the best the agency could provide given the competing demands it was facing.
"We think that there's a fair offer on the table, we re-shaped the offer last week, we added about an additional 16 million [dollars] to the deal and we really were hoping that the union would take that out to its members and test it."
Negotiations between Te Whatu Ora and the union would resume on Wednesday, Slater said.
Alexander Muthu, who was at the picket line in Auckland, told Midday Report it was frustrating to even ask for inflation-adjusted salaries.
"But it's very clear that the current conditions being offered are not able to attract new doctors to work here, and it's not enough to keep doctors working full-time in Te Whatu Ora."
'The work is endless'
The Nurses Organisation, which called off its own strike last month after members accepted an improved pay offer from Te Whatu Ora, has come out in support of the action by doctors and dentists.
President Anne Daniels said asking senior doctors and dentists to take a pay cut by not offering increases that match inflation was unfair and short-sighted.
She said health professionals were leaving their jobs at unprecedented rates.
"The work is endless, the pressures are high and the prospect of burnout is very real. Refusing fair pay lifts is just going to exacerbate the problem, causing more doctors to leave or retire early."
"It's hard enough right now to get an appointment with a doctor and this has already resulted in massive pressures on emergency departments, which affects us all. Te Whatu Ora's penny-pinching on wages will just end up costing the health system more in terms of pressure on other workers and remaining resources."
Daniels said that, like nurses, senior doctors and dentists cared about their patients and were going on strike for the good of their profession's future.
She said paying appropriate wages would reduce the number leaving for overseas or private sector positions.
Oncologist Siobhan Cross said money was important in attracting and retaining staff.
She said she and her colleagues wanted to work in a system where they could help make things better, not worse.