Nurses have passed a vote of no confidence in the health secretary Andrew Lansley, the first time this has happened in 30 years.
They are unhappy at plans for a major shake-up of the NHS in England.
Ninety-nine per cent of those who voted at a conference in Liverpool backed the motion.
The government claims most staff support the changes and that doing nothing is not an option, but says it will listen to the nurses.
What's happening to the NHS?
Ministers want to give GPs control of tens of billions of pounds of the health budget and encourage private companies to get more involved in providing treatment.
Doctors will be able to choose to send patients for treatment with any registered provider. That means private consultants would compete with NHS hospitals to get referrals from GPs.
Who's unhappy about it and why?
Labour opposes the plans, as do some doctors and other medical groups.
Critics say it could be risky to give big budgets to doctors, who are more used to looking after patients than managing money.
They are also worried about private health companies putting profits before patients.
The Royal College of Nursing says the changes will undermine the NHS. It is worried about front-line staff like doctors and nurses losing their jobs, even though the NHS budget has been protected.
What difference will it make to me?
If you're a patient - not much to start with.
You still won't have to pay to use the NHS, although everyone already pays for it through taxes. You'll still go to your local doctor as normal.
But the government hopes you'll have more choice over the type of treatment you get, and where you can go to get it.
Newsbeat has been speaking to staff at University College Hospital in central London...
Laura Dilworth, 28, staff nurse
"It would be better if the government listened to the NHS and the people within it a bit more.
"Morale isn't too bad at the moment but if people start to lose jobs and there are less people on the ground - then morale will start to decline."
Riya George, 21, volunteer, wants to be a doctor
Riya has been helping nurses while doing her degree.
"I really admire nurses. They work so, so hard. Really hearing them out would be a great thing because it's the nurses who do a lot of the care. It would definitely be wise to ask them their opinions."
Melanie Davies, 31, environmental monitoring officer
It's Melanie's job to make sure the hospital wards are clean.
"These are worrying times. Is my job going to be safe? To be honest I don't think anyone is safe.
"I'm a front line worker and I just hope to God my job is going to be safe at the end of it all."
