The Great Western Hospital in Swindon has earned £1.2m in parking fees since it opened three years ago.
The financial details have come to light after a Freedom of Information request by the BBC.
The hospital said although the figure was high and was a revenue, there were running costs directly associated with car parking.
Swindon & Marlborough NHS Trust was criticised in January because of parking charges of £35 per day.
Swindon Borough Council, which runs the car park on behalf of the hospital, has said the charges were in place to deter people parking there and travelling into town.
'Headline grabbing'
A hospital spokesman said maintenance costs and the wages of two parking attendants also came from the fees.
Trevor Payne, director of estates and facilities at the trust, said: "There are a lot of costs we need to take into account.
"We have contracts with the council to enforce car parking, we have machinery and equipment that we have to purchase for the ticket issue, we've also got lining to put down in the car park.
Yes, it is a headline grabbing figure, but there are also headline grabbing costs that go with that as well.
"From my experience, I've run a number of hospital car parking schemes and they're in line with other schemes.
"We have benchmarks to compare costs with other schemes as well. We've looked at policies and procedures, and car parking at hospitals is an emotive issue, but our costs are broadly comparable."
Mr Payne said the trust had an annual contract with the council to run the car park which came with two attendants.
He said it was "only right and proper" that the trust paid for that service.
"The system has been set up to cover costs. If there is any surplus left at the end of the year it is ploughed back into supporting the operational activity of the hospital - anything from linen to patient services."
