Thousands of health workers have marched through central London as part of a campaign against NHS reforms.
Organisers said about 7,000 staff took part in the "I Love The NHS" event which finished in Trafalgar Square.
TUC president David Prentice told the rally that the service must not be "sold off to private companies".
Bridlington GP Hamish Meldrum, chairman of the BMA's council, said: "As GPs, we're saying stop blaming us for the NHS's problems.
"Stop going on about us as overpaid and not working hard enough. It's actually the GPs who have the potential to help save the NHS."
London mayor Ken Livingstone sent a message to the demonstrators by video.
He said the NHS was the "single most important social advance of my lifetime".
TUC president David Prentis told the rally: "We are here today to tell the world that we will not allow our health service to be sold off to private companies on the altar of profit."
Health Minister Ann Keen commented that staff had endured a "tough" year but that the NHS had to keep pace with rising public expectations.
"The NHS budget will increase to £110bn in 2010-11, more than triple the 1997 total," she said.
"This extra investment, combined with increased efficiency, means we can focus unremittingly on improving quality, safety and access for all within a locally accountable and clinically led NHS."
Earlier, Karen Jennings of the Unison union said a health service that is free at the point of need and paid for by taxation should be cherished.
Mrs Jennings told BBC News: "We're coming up to its 60th anniversary, and we're very keen to get the message across that we've got quite an extraordinary health service in this country.
"One that is free at the point of use, one that is equal to all that need to use it, is paid for by direct taxation, and is probably one of the most efficient health services in the world."
She said despite criticisms by politicians and the press, surveys have shown that the vast majority of people who use the NHS are very satisfied with it.
She said: "Many, many comparable countries, their citizens really fear having to pay for their healthcare and whether they can afford it and we don't have these worries here.
"We've got something that is a very precious resource here and we shouldn't undermine the ethos that exists, and the founding principles on which the NHS is based."
Mrs Jennings said she was "very worried" about plans by the Conservatives to introduce more competition into the health service.
She said: "The big fear that staff working on the NHS have, and many, many local communities, is that you fragment the NHS if you make it too competitive."