Lab workers at the New Zealand Blood Service are planning to strike for 24 hours at the end of the month.
The workers include scientists and technicians who say they are being paid up to 28 percent less than lab workers at Te Whatu Ora/Health NZ despite doing the same work.
The service collects and processes blood products and other tissue from donors and makes sure they are safe for use.
The striking workers are at laboratories in Christchurch, Auckland and New Plymouth.