The Labour leadership has suffered a conference defeat as delegates backed criticisms of key planks of the government's pensions policy.
The protesters demanded "justice" on pensions
The conference passed a motion attacking plans to raise the state pensions age to 68 and delay restoring the link between pensions and earnings.
It also pressed ministers to do more to compensate workers who lost out on pensions when their firms went bust.
People whose pensions have been hit have protested outside the conference.
The pensions motion, tabled by the GMB union, welcomed many parts of the government white paper, including measures to make pensions provision fairer to women.
But it "opposes any suggestion that the state pension age be raised before health inequalities in the UK are eradicated and improved longevity is equally shared by all".
During the pensions debate on Monday, the GMB's Malcolm Sage said raising the pension age was not fair when people were expected to live to 68-years-old in Glasgow but to 74-years-old in Kensington.
Raising basic pension
The government has promised to fulfil long-held demands for the link between earnings and pensions to be restored - but probably not until about 2012.
The conference vote welcomed that pledge, saying it would make a substantial difference to many people's retirement income.
But it added: "Conference is concerned that delaying restoration until 2012 or beyond will leave an unacceptable number of today's pensioners reliant on inefficient means-tested benefits, much of which does not get through to those who need it."
Delegates demanded ministers speed up the restoration of the link and raise the state pension to at least £114 a week.
The motion also praised the government for setting up the financial assistance scheme and pension protection fund to help people whose occupational pension schemes go bust.
But it said the terms of those funds needed to be reviewed to make sure the government honoured its promises.
That call was bolstered by the pensions protest organised by the Amicus trade union.
Some of the protesters were due to meet Pensions Minister James Purnell to hammer home their concerns.
Amicus general secretary Derek Simpson said: "The cost of compensating these people is relatively low and can be spread over the next 50 years.
"Failure to do so will mean that people who have taken the government's advice and saved responsibly will face real poverty in retirement."
The organisers of the rally estimated 250-300 people had joined the protest.
Colin Perry, a former worker at Allied Steel and Wire (ASW), said he had paid pension contributions for 30 years and had now lost his pension.
Mr Perry, 52, from Cardiff, said back problems meant he could no longer work and he had no idea where he would get money for his old age.
"It's unfairness to all the workers, not just myself," he told BBC News. "We paid these things - they said we had to - and then you get rot."
Mick Leahy, general secretary of the Community union, told the demonstrators: "Gordon Brown and Tony Blair owe an obligation to use as working people that you get the pensions that you deserve."