Anaesthetic technicians at Rotorua Hospital have started their five-day strike.
The APEX union members are stopping work for 120 hours, until 8am on Saturday.
APEX, is New Zealand's specialist allied, scientific and technical union.
This week's strike brings the total industrial action by the Lakes DHB technicians to nine 24-hour days since October last year.
They have been bargaining their collective agreement with the Lakes DHB since October 2017.
APEX advocate Luke Coxon said, "The DHB is postponing or cancelling hundreds of elective surgeries, at an estimated cost of hundreds of thousands of dollars."
"This includes sending patients to private hospitals. It is mind-boggling that the Minister of Health would be so short sighted as to let this happen. The people of Rotorua deserve better; this strike should not be happening."
Lakes DHB said APEX's claims that the Minister of Health, Dr David Clark, was responsible were "incorrect and misleading".
It said the New Zealand Public Health and Disability Act 2000 allowed DHB chief executives to enter into a collective agreement subject to consultation with the Director-General of Health.
Lakes DHB employs 11 anaesthetic technicians who mainly work in operating theatres helping anaesthetists.
They check and maintain the equipment and drugs available, help insert airway devices and tubes into veins and arteries, and act as patient advocates.
As part of the consultation process, settlement offers are assessed against the Government Expectations on Employment Relations in the State Sector.