Doctors have called for radical changes in the way the NHS in England is run.
Doctors say resources are finite
The British Medical Association says the NHS should only provide core services - agreed after a public debate - because resources are limited.
It is also calling for the NHS to be managed by an independent board to take the day-to-day running of the service away from political control.
The government rejected limiting NHS services, and said change had to result in a better service for patients.
The BMA proposals are contained in a paper setting out a vision of the future for the NHS.
James Johnson, BMA chairman, said there needed to be an end to 'constant political dabbling' in the NHS.
The BMA says the constant development of new, effective, treatments and drugs - plus the fact people are living longer - means rationing is already happening in the NHS.
It says the suggestion of a list of core services is designed to recognise the NHS cannot pay for everything, but to make the service fair and equitable.
Mr Johnson said: "The NHS should provide a comprehensive range of services, available to all on an equal footing.
"If we are going to retain an equitable, universal approach within limited resources then priority setting is inevitable.
"Politicians need to acknowledge this and that it happens already but in a non-transparent and piecemeal fashion.
"A clear and transparent approach is needed."
Hamish Meldrum, head of the BMA's GPs committee added: "The core services the NHS provided would be very substantial and should cover the necessary services for core health care."
The BMA's proposals for an independent board would see the establishment of a board of governors who would be appointed by ministers.
They, along with an executive management board, would control the day-to-day running of the health service.
This, says the BMA, would free up ministers to consider broader health policy, particularly on public health issues which could help reduce health inequalities.
The proposal for an independent board is not backed by Prime Minister Tony Blair or, it is understood, his likely successor Gordon Brown.
However, BMA leaders say they believe it is the best way forward, despite the lack of success of similar schemes in Oregon in the US and in New Zealand.
The NHS should also have a written constitution, the BMA says, which would be a "written agreement between the government, the NHS and the public".
It would set out the NHS's core values, and would contain a charter setting out what the public could expect from the NHS - and what the NHS could expect from the public.
The BMA's report, which will be discussed at its annual conference in July, also suggests limiting the involvement of the private sector in the NHS.
It says the private sector should only be used "when there is no NHS capacity", and that it should be used to "support rather than supplant" the health service.
The report also calls for public involvement in the running of the NHS to be bolstered through the establishment of new elected local health councils.
Health Minister, Andy Burnham, said further independence within the NHS should only be considered if it led to improved services.
On core services, he said: "We resist any call to make the NHS a slimmed-down, emergency service, because that's what it would become if we started rationing care.
"The only losers would be the poorest people. The NHS should continue to be comprehensive and universal."
Shadow Health Secretary, Andrew Lansley, said: "I am disappointed with the BMA's pessimistic attitude to the future of the NHS.
"Over the last decade NHS productivity has fallen; NHS staff have been disempowered and become demoralised and the NHS has become more bureaucratic.
"But if we can reverse all these there is great potential for delivering our healthcare needs."
Nigel Edwards, director of policy at the NHS Confederation, said: "We need to confront the reality that if the public do not want cost to be a factor in NHS decisions than they may have to prepared to pay more in order to have every treatment funded."