Thousands of doctors specialising in the care of older people believe the NHS is institutionally ageist, a survey suggests.
A British Geriatric Society survey of 200 doctors found that more than half would be worried about how the NHS would treat them in old age.
The government says age discrimination legislation will be part of the forthcoming Equality Bill.
But Help the Aged warned it may be more than a year before that is approved.
Kate Jopling, head of public affairs for the charity, said: "Older people have a right to fair health care, free from ageist prejudice."
The charity believes that the current proposals will not be approved before the next election and are calling on the government to review their timetable as a matter of urgency.
The survey of just over 200 doctors showed that two-thirds think older people are less likely to have their symptoms fully investigated.
Of those polled, 72% said older people were less likely to be considered and referred on for essential treatments.
And more than half the doctors said they themselves would be worried about how the NHS would treat them in old age.
Alex Mair, chief executive of the British Geriatrics Society, said: "What this research makes clear is that the NHS is currently failing older people.
"We need to ensure that patients of all ages receive the very best care, regardless of their age.
"The proposed age regulations for health and social care will be integral to changing attitudes and ultimately improving care. The sooner we have these regulations in place the better it will be for older people."
The government has said it will take about 18 months to draft the bill.
Care Services minister Phil Hope said: "It is vital we get the legislation right to ensure there are no unintended consequences - such as service providers withdrawing beneficial age-based practices.
"We need to bring in changes over time, to make sure we get it right.
"We're not waiting for legislation to take action. The government is working with health and social care providers, commissioners and professional bodies to help them assess what practices they need to change to eliminate discrimination, ahead of legislation. "
The British Medical Association said it was very worried about ageism in the NHS and would soon be issuing guidance to its members to help them tackle the problem.
A spokesman said: "Institutional and unconscious ageism is not just a problem for the health service but for society as a whole.
"It's very important that older people are not seen simply in terms of stereotypes, for example, that they should put up with symptoms perceived as normal for older people whereas if they were younger they would be referred for investigation.
"The BMA is particularly worried about older people from different ethnic minorities because they are likely to be doubly stereotyped because of their age and their minority group.
"Older people often suffer a loss of dignity in the NHS because of mixed wards and shared bathing facilities. It is essential that politicians, NHS managers and health professionals realise this and aim to improve the situation for older people.
"Everyone in society has an interest in ensuring older people's rights are respected. If we are not currently old ourselves, we will be one day."
Jo Webber, deputy policy director of the NHS Confederation which represents over 95% of the NHS organisations, said: "A lot can be and is already being done without the support of legislation.
"Essentially, this issue is about the practicalities of implementation. NHS doctors and nurses across all fields must work together to provide the services that meet the needs of older patients on an equitable basis.
"The service needs to ensure that elderly patients and their carers are involved in all decisions about their care and that the care given is personally appropriate, of high quality and responsive to individual need regardless of age."