People with learning disabilities receive worse healthcare than the rest of the population some doctors and nurses believe, according to a charity.
Mencap has found almost half of doctors and a third of nurses from a poll of poll of 1,084 think this is the case.
It is urging health trusts to sign a charter which sets out the rights of people with learning disabilities and the responsibilities of hospitals.
The government says that removing inequalities is a priority.
Mencap's research - conducted by ICM among more than 1,000 doctors and nurses within the past month - also revealed 45% of doctors and a third of nurses had witnessed a patient with a learning disability being neglected or being denied their dignity.
Four out of 10 doctors and a third of nurses surveyed thought that people with learning disabilities were discriminated against in the NHS.
Despite enjoying legal protection, the survey found learning disabled people were being failed because more than a third of health professionals had not had appropriate training.
Yet a majority of doctors and nurses admitted to needing specific guidance on how to meet the needs of learning disabled patients.
Disability legislation requires health care providers to make "reasonable adjustments" to accommodate disabilities and long-term health conditions.
In the case of learning disabled people, a reasonable adjustment might include: allowing more time for consultations, using a patient's preferred method of communication and using their hospital passport.
A hospital or health passport is a document carried by a patient that includes key information about their condition, their likes and dislikes and things that they feel are important.
"Healthcare professionals have recognised they need more support to get it right when treating people with a learning disability," said Mencap Chief Executive, Mark Goldring.
He said that the charity's campaign called - Getting it Right - aims to ensure that ignorance need never be the cause of a learning disabled person's death.
"Our charter sets out a standard of practice and will make health trusts accountable to people with a learning disability, their families and carers."
Twenty-six year-old Emma Kemp had a 50% chance of surviving the cancer with which she was diagnosed, according to her mother, Jane.
But hospital staff were apparently worried that her learning disability would make her difficult to treat, so they decided not to treat her.
Eventually, Mrs Kemp agreed that her daughter should receive palliative care.
"She was denied her chance of life by doctors who discriminated against her," said Mrs Kemp.
Mrs Kemp asked one of her daughter's doctors what would happen if Emma hadn't had learning disabilities and she was told that treatment would begin immediately.
"When I agreed that Emma should only receive palliative care treatment, I did so because I was then told that Emma only had a 10% chance of survival and that it would be cruel to treat her," she said.
"I now know that this was not true; that I was misled into agreeing with the decision that cost my daughter her life."
The Getting it Right charter asks health professionals to:
• Ensure that "health passports" are available and used
The Department of Health says that, while improvements have been made, there is still "much to do".
"Health remains one of the three priorities for the government's learning disability strategy," a spokesperson said.