NHS hospitals raked in more than £110 million in car parking charges last year, research by the Liberal Democrats revealed.
The figures, disclosed in a Freedom of Information request, showed visitors were hit with £84 million in parking fees while NHS staff were charged £28 million.
Addenbrooke's Hospital in Cambridge made the most out of any hospital, taking £2.8 million in parking charges.
Peter Wilcock, Liberal Democrat candidate for Saffron Walden, Cambs, said the parking charges were "effectively a tax on the sick".
"No one is denying the need for hospitals to cover their costs but that doesn't mean they can use hidden charges to help themselves out of financial black holes.
"Ministers have ducked this issue for far too long and failed to ensure that Government guidelines are actually being followed."
Stephen Robinson, Liberal Democrat candidate for Chelmsford, Essex, said: "I raised the charging issue when I met Broomfield hospital managers last year and will do so again.
"Mid Essex Hospitals must cut their "tax" on patients - excessive car park charges, high bedside phone and TV charges and expensive 0844 phone numbers.
"We now need an urgent review into whether hardworking doctors and nurses and the chronically ill should be paying these charges at all."
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