Health professionals who provide radiation services to cancer patients have voted to go on strike after four months of unsuccessful negotiations.
Apex, which represents them, said it had been trying to secure pay rises for medical physicists and the employers' offer of a 1 percent rise this year, as part of a three-year agreement, was not good enough.
Apex advocate David Munro said New Zealand was competing in an international market to attract and retain the physicists.
He said, compared with Australia, salaries in New Zealand were up to 50 percent behind.
District health boards say a medical union's threat of strike action deliberately targets vulnerable cancer patients.
However, Mr Munro said there were plans in place which mean patients' health would not be put at risk.
The DHBs said the action was surprising, disappointing and unnecessary, and that mediation was the best way to resolve the dispute.