A national review of end-of-life care has found many hospitals are failing to provide face-to-face palliative care specialists around the clock.
The review shows only 16 of 142 hospital sites offer specialists on site 24/7.
The report is the first since the controversial Liverpool Care Pathway was scrapped.
NHS experts acknowledge steady improvements in the last two years, but warn there is still work to do.
The Liverpool Care Pathway was phased out amid criticisms it had been misused as a tick-box exercise, leaving some patients without food and water.
In its place a series of guidelines has suggested moving away from a one-size-fits-all approach, instead focusing on individual care.
This report, led by the Royal College of Physicians, shows there have been broad improvements in all areas.
Researchers found, for example, that communication with patients and relatives had improved.
But there were still a number of concerns.
In 18% of the 9,000 patient notes researchers examined, there was no written evidence to suggest that do-not-resuscitate decisions had been discussed with relatives or friends.
And in around 3,000 notes there was no evidence that the patient’s ability to eat and drink had been assessed on the last day of life.
But the researchers’ main concern was that many patients and doctors did not have full access to on-site palliative care specialists at evenings and weekends.
The majority of hospitals did offer a specialist telephone helpline at all times and 53 of 142 hospital sites offered face-to-face palliative care on Monday to Sunday between 9am to 5pm.
But for 26 trusts there was no record of face-to-face specialist palliative care involving doctors at any time.
Study-lead Dr Sam Ahmedzai, argues the situation is not good enough.
He said: “We know that most front-line doctors and nurses giving end-of-life care do it to a very good standard.
“But the problem happens when things start to go wrong and often they go wrong out-of-hours in the middle of the night and at weekends.
“Then doctors and nurses who may be inexperienced need to be able to access specialists in palliative care.”
He says without this, patients with complex problems may not get the care they need.
Julie Coombes’ father found out he had bowel cancer in May 2015. He was in and out of hospital for three months. But Ms Coombes, 33, from Plymouth, says her father didn’t feel he had good care there. She says his symptoms and sickness couldn’t be controlled, so the family decided to take him out of hospital to die at home.
She said: “While he was in hospital the palliative care team came for about five minutes, while he was in his bed with everyone around and just said you are going to die.
“Apart from that we did not get any leaflets or any help… It is not something I would want anyone else to experience.”
Dr Kevin Stewart, of the Royal College of Physicians, said in general he was encouraged by the improvements.
But he added: “We are disappointed that there are still major deficiencies in the provision of specialist palliative care at nights and weekends by many trusts; patients and their families deserve the same level of service whatever the day of the week.”
Dr Adrian Tookman, at the charity Marie Curie, which part-funded the review, said “We can’t ignore the fact that the vast majority of dying people and those close to them still have limited or no access to specialist palliative care support when they need it in hospital. This is not right, nor good enough.
“Care of the dying has no respect for time, so if we are to deliver a consistent 7-day service by 2020, it is critical that funding is directed towards recruiting and training doctors and nurses to provide specialist care now.”
NHS England, which commissioned the review, welcomed the improvements, but said it was clear that more could be done.
A spokesperson added: “Although this audit presents a snapshot of end-of-life care within NHS hospitals, there are clear variations in the support and services received – and there are areas where improvements must continue to be made.”