Lakes District Health Board will spend the next two days with a gaping hole in its staff pool as junior doctors strike.
It employs 93 resident medical officers and most are members of the Resident Doctors' Association (RDA).
RDA members across the country are walking off the job from 7am today, for 48 hours.
Rotorua Hospital general surgical registrar, Dr Kopa Manahi, is striking to "retain NZRDA approval for clauses that require their agreement".
"I believe this term is a necessity for the protection of our members who may lack the knowledge and experiences required to deal with what can be complex employment matters."
• Junior doctors' strike: What you need to know
Dr Manahi said his relationship with colleagues working during the strike remained professional, despite "differing opinions", and he was confident in Rotorua Hospital's contingency plans.
Lakes DHB has cancelled elective and scheduled surgeries, affecting 20 patients across the two days, and outpatient clinics, affecting 350 people.
Staff will focus on those most in need in emergency departments in Taupō and Rotorua.
Rotorua Area Primary Health Services chief executive Dr Kirsten Stone said "our health sector, as a whole, works hard and the pressure we are all working under is not always visible".
"Industrial action is part of the normal course of a very large workforce... everybody working in the health system wants the absolute best for their patients but sometimes to get that you have to do what's best for the workforce."
The RDA gave notice of this week's strike on New Year's Eve.
It said DHBs were trying to reverse some of the improved working conditions secured after the 2016 strikes.
DHBs "strongly dispute" this.
Last week the DHBs' spokesman Dr Peter Bramley said they had tried to negotiate an agreement where clinicians and hospital managers could work with their junior doctors to make rostering decisions, "rather than the union".
Acting Lakes DHB chief executive Nick Saville-Wood said contingency planning meetings started several weeks ago and apologised for the disruption to affected patients.
"Changes to hospital operations are considered necessary to ensure the safety of our patients and staff."
On Friday the RDA announced plans for a second national strike, between January 29 and 30.
Lakes DHB strike advice
- Make sure you're up to date with prescriptions.
- For minor health issues, make your GP the first port of call.
- You can also contact Healthline on 0800 611 116 for advice from a registered nurse.
- Affected patients have been notified but uncertain patients can ring 0800 223 647 to check.