Hospital attendants at Waikato Hospital are going on strike for 24 hours on Thursday.
The 100 attendants, members of Unite Union, want to be paid the living wage.
Attendants do tasks such as transporting rubbish and laundry; sorting mail; and moving specialised medical equipment and patients.
Unite national secretary Gerard Hehir said $20 an hour was absolutely justified as a base rate for the work.
He said Waikato District Health Board was claiming that because some attendants get paid night or weekend rates they were already getting a living wage.
They have been negotiating with the DHB since November last year.