Hospital workers have staged a demonstration against the introduction of £120-a-year car parking charges.
Hospital staff demonstrate outside the Ebbw Vale hospital
Gwent NHS Trust has brought in staff fees at Ysbyty'r Tri Chwm in Ebbw Vale, and may do the same at Newport's Royal Gwent and Nevill Hall in Abergavenny.
It said the money would be used to improve security at the site for patients and hospital workers.
But staff, who will meet managers on Tuesday, said there should be free parking at hospitals throughout Wales.
Mike Markey, a staff nurse at the hospital and a Unison representative said: "The trust introduced these parking charges at the beginning of April and we were very angry about it.
"They are charging us £120 a year for the privilege of coming into our own workplace.
"We're not just here to protect our own interests but those of patients and relatives too."
"They say it's about facilities, but these are facilities they should supply as an employer," said Mr Markey
"We shouldn't have to pay for the privileges of security, CCTV etc and if they want to make us the same [as patients and visitors to the hospital], then make it free for everyone in Wales.
"We have had widespread public support and also I've received support from other hospitals across Britain," he added.
A spokesman for the trust said: "Charging for car parking is now standard practice in virtually every trust in south Wales.
"We will continue to work with staff and their representatives to reach agreement at Ysbyty'r Tri Chwm, but we must maintain equity with all our staff who currently pay charges on other hospital sites.
"Income generated is reinvested in improved parking, CCTV, extra security and maintenance that will ultimately benefit not only staff, but also patients and visitors to our hospitals."
Staff at the hospital will meet management on Tuesday morning to discuss the dispute.
The Welsh NHS Confederation, which represents all trusts and local health boards, said many hospitals had limited space, but demand for parking space kept rising.
"Providing free parking for all could mean that patients and visitors cannot park because spaces are being used by unscrupulous people who take advantage," it said.
"On occasions, increasing congestion has even made it difficult for ambulances to access hospital entrances. This is one reason why charges are sometimes used - as a way of managing demand."
But the confederation said it was important to understand that fees were not "about making a profit out of patients."
"It is about managing demand, trying to ensure access for patients and visitors is protected, and covering the considerable costs - such as land, security, signage and lighting - of maintaining a car park."