Dying people are being left with inadequate round-the-clock pain relief and poor access to specialist help, according to new research.
They are caught in a postcode lottery which affects whether their families are able to secure proper NHS end-of-life care on weekends and during the night, it suggests.
In some parts of England, NHS bosses only provide a telephone advice line to cater for people in their last days of life.
Meanwhile, others have full palliative care teams with expertise in areas such as controlling cancer pain or lessening distress.
The research is based on Freedom of Information (FoI) requests made to clinical commissioning groups (CCGs), which control millions of pounds of NHS money and are responsible for arranging care for patients.
The study, led by Baroness Ilora Finlay, an independent cross-bench member of the House of Lords and world expert on palliative care, found the "provision of round-the-clock access to specialist palliative care and pain control is inconsistent".
Some regions only offered "basic" services such as a phone line with no access to consultant advice, while others ran dedicated night-time services, including access to consultants and nursing teams.
Just under a third of CCGs had specialist pain control teams but most of these operated only in normal working hours, with no cover overnight.
The report found there was a heavy reliance on hospices to plug gaps, even though many of these had too few beds to cater for people in need.
Hospices receive a third of their funding from the Government, councils and the NHS but most have reported freezes or reductions to this funding.
Every year, about 200,000 people are served by hospices, which must raise £1bn a year as charities.
The new research found wide variation in access to specialist palliative care beds, with one CCG commissioning 61.65 beds per 1,000 people and another commissioning 0.55 per 1,000 people.
The report also found the amount spent on palliative care per patient per year ranged from £51.83 to £2,329.19.
Confusion over services meant that people's choices over where to be cared for and where to die were not always honoured, it said.
Only half of CCGs said they were committed to improving their services in the future, it added.
The researchers concluded: "Our data reveal that the devolution of decision-making down to CCGs suggests that palliative care provision is not being considered as a core service in some parts of England.
"Despite much evidence of its cost efficacy, the provision of specialist palliative care is in need of a national framework to ensure that patients achieve good end-of-life care everywhere."
A report last year from the Office for National Statistics (ONS) found that some people in their final days of life were not getting enough help to eat or drink and were dying in pain.
One in five people who saw their relative or friend die in the previous 12 months also felt decisions were taken about their care that the person would not have wanted.
A May 2015 report from the Parliamentary and Health Service Ombudsman (PHSO) also found failings in palliative care, including poor symptom control, poor communication. and inadequate out-of-hours services.
Alex Robertson, executive director of external affairs and strategy at PHSO, said of the new study: 'It is deeply worrying that good end-of-life care remains a postcode lottery.
"We have seen horrific cases of people dying without dignity, where they have been left in pain and their final wishes not communicated with their families.
"NHS commissioners must understand local peoples' needs so they can provide the best possible care and Government must support them and monitor progress."
The new study was published in the journal BMJ Supportive and Palliative Care.
Baroness Finlay said: "How someone dies remains in the memory of those they leave behind, so it's vital to get this right, and that requires good planning based on good information.
"From the moment someone receives a terminal diagnosis, palliative care has a role to play in supporting them and their family.
"We must ensure that people who need expert palliative care can access the care they need when and where they need it."
Jonathan Ellis, director of policy and advocacy at Hospice UK, said: "Hospices play a vital role in meeting people's needs and have much to offer in making sure people get the right end-of-life care, day or night.
"However, we can only achieve this if improving end-of-life care is a local priority and services are appropriately recognised and commissioned to meet people's needs.
"Many Clinical Commissioning Groups work closely with their local hospices, but we still need to see local health bodies take more responsibility and prioritise end-of-life care if we are to achieve the Government's commitment."
Professor Bee Wee, NHS England's national clinical director for End of Life Care, said: "International comparisons rate the UK as the best country in the world for end-of-life care, and a recent survey again found that three-quarters of bereaved people rated the overall quality of care for their relative as good or better."