Some NHS hospital trusts are making more than £3 million a year from car park charges, an investigation has found.
Year on year, hospitals across England are raising increasing amounts of money from staff, patients and visitors, including those who are disabled, the Freedom of Information study by the Press Association found.
Hospitals are also handing over millions of pounds to private firms to run their car parks for them, and allowing some to cash in on parking fines.
Others are tied into private finance initiative (PFI) contracts, where all the money raised from charging ill patients, staff and visitors goes to private firms under lengthy contracts.
Of more than 90 trusts that responded to the FoI request, half are making at least £1 million a year.
Seven NHS trusts earned more than £3 million in 2014/15 from charges, a further eight made more than £2 million a year while a further 32 earned more than £1 million a year.
Almost half of all trusts also charged disabled people for parking in some or all of their disabled spaces.
Many trusts defended their revenues, saying some or all of the money was put back into patient care or was spent on maintaining car parks or grounds.
Others claimed their sheer size and the fact that they serve busy neighbourhoods meant they took more in revenue.
Oxford University Hospitals NHS Foundation Trust raised £3,728,000 net in 2014/15, of which it listed £2,957,000 as "costs" such as running the car park office, security and legal fees. Oxford University Hospitals NHS Foundation Trust say the fees are in keeping with local parking prices and haven't been increased for two years.
Katherine Murphy, chief executive of the Patients Association, said it was unfair that hospital parking in Wales and Scotland was largely free but patients in England are still forced to pay.
"We are concerned that hospitals in England still charge patients for car parking," she said. "Why is it that patients in Wales and Scotland do not have to pay to park? It is a postcode lottery and a tax on sick people who sometimes struggle to pay.
"The money is never reinvested in frontline services. Hospital car parks are often managed by private contractors who take a huge percentage of the profits.
"This is morally wrong - and charging disabled people is a disgrace."
The investigation found that some hospitals were built under PFI contracts, with all money from parking going to private companies under the terms of the scheme.
Some NHS trusts also raised a significant amount from charging staff for parking. University Hospital Southampton NHS Foundation Trust took £3,876,314 in parking charges in 2014/15, of which £1,206,836 was from staff. The trust says it complies with guidance and their charges are in-line with other local parking charges. They say the figure quoted is gross income, which includes staff car parking income and costs to run the car-parks as well as patient and visitor income.
Shadow health minister Andrew Gwynne said: "When patients go to hospital, the last thing they want to worry about is keeping the car parking ticket up to date. For some patients and their families, the costs can really rack up, which is why these figures are so worrying.
"The last Labour government had a plan to phase out car parking charges, but recent attempts to discuss this matter in Parliament have been blocked by Tory MPs."
Rosie Downes, senior campaigns officer at Macmillan Cancer Support, said: "The core principle of the NHS is to provide free healthcare for all at the point of access.
"But sadly these latest figures show that some cancer patients in England are still paying extortionate hospital car parking charges in order to access treatment for a life-threatening illness.
"Cancer patients receiving vital treatments such as chemotherapy and radiotherapy will often need to make frequent trips to hospital and unaffordable charges are leaving many out of pocket."
A Department of Health spokeswoman said: "We expect all NHS organisations to follow our guidelines on car parking, including offering discounts to disabled people.
"Patients and families shouldn't have to deal with the added stress of unfair parking charges and our guidance rightly helps the public hold the NHS to account for any unfair charges or practices."
Hospitals that made the most money from parking are:
University Hospital Southampton NHS Foundation Trust £3.87 million
Oxford University Hospitals NHS Foundation Trust £3.72 million
Heart of England NHS Foundation Trust £3.41 million
East Kent Hospitals University NHS Foundation Trust £3.25 million
Sheffield Teaching Hospitals NHS Foundation Trust £3.16 million
University Hospitals of Leicester NHS Trust £3.12 million
University Hospitals of North Midlands NHS Trust £3.07 million