DHBs each have their own plan for coping with the strike and patients who had been given an appointment falling during the strike are encouraged to check their DHB's website for details. Some DHBs say they will contact all patients with care booked during the strike, while others say they will only contact those whose appointment is being changed.
Auckland DHB says it has been contacting patients whose care has been rescheduled.
"... if you haven't been contacted by one of our team at Auckland DHB, you should come to your scheduled appointment.
"Please be assured that all patients who need immediate hospital-based attention will still receive the treatment they require. However, people with non-urgent injuries may experience a longer wait.
"If your condition is not urgent or severe please contact your GP, Healthline [0800 611 116] or one of the after hours services where possible. As with any other time, if you have an emergency please don't hesitate to call 111."
The Waikato DHB says it has been forced to postpone and reschedule a number of outpatient clinics, mental health clinics and non-emergency surgery because of the strike.
The DHB is rescheduling about 400 outpatient appointments and 100 inpatient appointments so senior doctors at Waikato Hospital can focus on patients in the emergency department, intensive care unit and the maternity unit.
All patients whose operations or clinical appointments are affected by the strike are being notified by telephone or mail. Not all clinics are being rescheduled, so the DHB is asking patients who have not been notified to attend their appointment.
The DHB says it employs 420 junior doctors, mostly working out of Waikato Hospital, and about 70 per cent are members of the Resident Doctors' Association (RDA) union. The hospital is planning for all members to strike.
Dr Doug Stephenson, acting chief medical officer, said: "Our junior doctors make up the bulk of our medical workforce and we are highly dependent on them.
"We will need to reduce the number of patients in the hospital over the period leading up to and during the proposed industrial action, deferring planned surgery and clinic visits, which creates a lot of angst for our patients.
"This will be the third time in four months we've had to shift all of our energy and a significant amount of time to cover the roster to assure patient safety. Although the second strike was called off in November, much of the planning had already been done."
The Waikato DHB's hospitals in Thames, Te Kuiti, Taumarunui and Tokoroa are mostly unaffected by the strike.
Stephenson said: "We appreciate our senior doctors' assistance and will be doing all we can to provide them with support during the strike.
"We are reminding the public to keep our emergency department for emergencies only. If your illness or injury is not urgent you may face long delays. It's better to go to your family doctor or local private accident and medical clinic when symptoms first appear rather than becoming seriously ill and needing emergency services."
• Waikato Hospital has set up a helpline number for those who are unsure about their appointment: 0800 276 216.