The Waikato District Health Board is rescheduling 500 patient appointments in anticipation of a strike next week.
Junior doctors, who went on strike in October, have given notice of a second strike over rosters and pay.
The DHB employs 420 junior doctors, most of them at Waikato Hospital.
It said it was rescheduling about 400 outpatient and 100 inpatient appointments so senior doctors could focus on emergency, intensive and maternity care during the planned 72-hour strike, from 7am Tuesday.
Acting Chief Medical Officer Doug Stephenson said the DHB has put in place a contingency plan to ensure patients' safety during the strike period.
"We will get through this to the best that we can, we will ensure that patients are safe, we will take care of the acute emergent needs of our patients in the Waikato, but by no stretch is this optimal."
Affected patients were being contacted by phone or mail, but the DHB said anyone uncertain about an appointment should call 0800 611 611.
It said not all clinics were being rescheduled, and any patients who had not been notified should attend their appointment.
Mr Stephenson said the Thames, Te Kuiti, Taumaranui and Tokorua hospitals were mostly unaffected.