Health workers from across England rallying outside Parliament have heard the government's handling of the NHS called "a disgrace".
Health staff make their way to Parliament for the rally
Hundreds of campaigners joined a rally and lobbied MPs over NHS cuts and privatisation in the strongest show yet of opposition to changes in the NHS.
Unison general secretary Dave Prentis highlighted opposition to NHS cuts.
But Prime Minister Tony Blair defended the government's record on reforming the NHS and cutting waiting times.
Challenged by Tory leader David Cameron in the Commons about the protest, Mr Blair said: "Of course, there are changes taking place, rightly because there are more cases being done on a day case basis, new technology is shortening waiting times and specialist care is being developed.
"All of this is part of necessary change.
"The only way the NHS is going to improve is keep the money coming in, not cut it back, which is your policy, and make sure we make the reforms, which add value for money."
Doctors, nurses, midwives, cleaners and other support staff descended on London under the umbrella of NHS Together, an alliance of 16 unions warning job cuts and continued reforms risk "fragmenting" the health service.
Health staff were joined by members of the National Pensioners Convention and national campaign Keep Our NHS Public.
They say that 20,000 posts are being cut - although the government says only 900 staff will actually be made redundant, with the other cuts made through natural wastage and voluntary redundancy.
Over recent years, the government has increasingly relied on private involvement through independent sector treatment centres, which carry out minor surgery, and PFI schemes, which use private money to build new hospitals.
Some of the NHS's major acute hospitals are also coming under threat as local health bosses carry out reviews of services to make the health service more efficient.
Mr Prentis told protestors: "People were mystified by the health secretary's claim it was the best year for the NHS.
"It is the best year for private companies taking over the NHS."
But he added: "This was hardly the view of patients whose services faced cuts."
He was joined on the stage by Beverly Malone, general secretary of the Royal College of Nursing.
She said: "No one is saying no progress. Standing still is not an option.
"But when you reform, you have to reform for the right reasons and in the right way.
"You don't go in with your ears closed to the warnings."
Stephen Campion, chief executive of the Hospital Consultants and Specialists Association , told a meeting of NHS Together at Methodist Central Hall, near Parliament Square: "The tragedy is that the health unions and the government, whilst so close in recognising the need for change, are very close to one of the most divisive and damaging relationships since those bad days of the 1980's."
Frontline workers also addressed the rally.
Mandy Robotham, a midwife at Stroud maternity hospital added the NHS has an admirable midwifery service but is, like many parts of the NHS is 'fighting for its survival'.
The protest comes as a YouGov poll of 2,000 people showed more than half believed the NHS had got worse in the last decade.
Ministers have said they will listen to the views of the health staff who gather at Westminster.
But Health Secretary Patricia Hewitt said the government was committed to pushing ahead with its reforms.
"If we know that change will deliver better quality care and better value for money for taxpayers, then standing still is simply not an option.
"However, what will never change is our commitment to safeguard NHS values," she said.
But Liberal Democrat health spokesman Steve Webb said: "This lobby shows the depth of opposition within the NHS to the government's rushed reforms that are causing so much damage."