A new poll by the BMA has found that half of all people expect they will have to pay towards some of their NHS treatment within the next 10 years.
The survey of more than 1,000 people found that, while 93% agree or strongly agree the NHS should continue to be funded from taxes and remain free to users, many believe they will have to pay extra towards services.
Some 42% of people think the NHS is better now than it was 10 years ago, but 36% do not agree. Just over half (51%) oppose the government's policy of encouraging private firms to run NHS services, and 58% disagree with firms making a profit for their shareholders from providing NHS care.
The BMA's chairman, Dr Hamish Meldrum, said patients' fears that they will have to pay for aspects of their care could be fuelled by the government's increasing use of the private sector.
"The public may also fear that with rising drug and treatment costs, advances in medical technology and increasing demand for services, the NHS will no longer be able to afford a completely comprehensive health service," he said.