District Health Board admin staff say they need a pay rise of between 15 and 45 per cent, as their work is being undervalued.
The Public Service Association organised a flashmob in Wellington's Midland Park today to draw attention to the issue.
Members say the admin work is at the heart of hospitals around the country, but their expertise is undervalued because it's seen as "women's work".
The PSA has raised an equal pay claim with all the DHBs in New Zealand.
Amin worker Nancy McShane said staff felt "under siege", having to do their jobs in an environment where patients often became violent, sometimes under the influence of meth.
She said admin staff regularly had to provide emotional support to doctors and nurses.
"Without us there to book surgeries and manage waiting lists, look after their documentation for them, they would be focusing on a lot of administrative tasks that they really shouldn't be doing.
"Our hospitals would literally grind to a halt if we weren't there.
"I'm troubled by the recent assaults, we've had nurses being strangled by patients, sometimes multiple patients attacking one nurse.
"We're the background people that they go to for support, they need to be able to have those conversations with people who they know have their back."
McShane said they were inspired by the caregivers' pay equity win, and that their work was similarly undervalued.
"Some of us are on less than the living wage, and have been for years.
"We've had our wages frozen for five years. We're constantly only getting increases below the cost of living.
"A lot of us could be earning more working in hospitals as cleaners, rather than what we're doing."
PSA National Secretary Erin Polaczuk said admin and clerical work had been overlooked for a long time, with the DHB workers some of the lowest paid in the sector.
"For equal pay we're talking about gender-based discrimination and ongoing injustice, so this is different from their collective bargaining rounds.
"For us, this is a long-term strategy, we're going to keep chipping away at it, and the time will come for these members."
Polaczuk said the push for a 15-45 per cent pay raise came from assessing the work of the DHB admin staff, and comparing it to similar work being carried out in male-dominated jobs.
"If your admin workers weren't there in the hospital, the place couldn't run.
"The clinicians rely on them to have the equipment and the rooms ready, we rely on them as patients to make sure we have notification of the appointments and that they actually happen.
"It's quite invisible work, but it's also vital."