Eleven terminally-ill people in Scotland every week are suffering in pain as they die, according to a new report by a group campaigning for assisted death to be legalised.
Dignity in Dying said even with high levels of palliative care, hundreds of patients still had no relief from their pain at the end of life.
Opponents of changes to the law have argued the risks are too high.
It comes as Scot Richard Selley travels to Switzerland to end his life.
The 65-year-old former teacher, of Glenalmond, near Perth, has chosen to die in Zurich later this week after a four-year battle with Motor Neurone Disease.
He told BBC Scotland: "Dignitas is giving me the chance to end my life in a painless and peaceful way.
"I bitterly regret, however, that I am prevented from doing that here at home."
The new report, called "The Inescapable Truth About Dying In Scotland", contains interviews with GPs, palliative care consultants and nurses, terminally-ill patients and bereaved families.
As part of research commissioned for the report, the Office of Health Economics concluded that "even if every dying person who needed it had access to the level of care currently provided in hospices, 591 people in Scotland a year would still have no relief of their pain in the final three months of their life".
Ally Thomson, director of Dignity in Dying Scotland, said: "The report really exposes the truth of how some people are dying in Scotland just now, and shows that 11 Scots a week can expect a bad death.
"These people are, in effect, collateral damage of a law which prohibits assisted dying and what they really need, for when palliative care stops working, is the option of an assisted death."
The report recommends assisted dying is legalised in Scotland "to give terminally ill, mentally competent adults a further option of escaping or avoiding a period of unbearable suffering at the end of lives".
That is a view shared by Mr Selley and his wife Elaine.
Since they revealed their plans to travel to Zurich they have received hundreds of cards, letters and emails of support.
"I have been overwhelmed by the support I have had from people," said Mr Selley.
He will end his life on Friday.
"Knowing that I will die very soon is a surreal experience, but it is my choice," he said.
Mr Selley, who has to talk-type to communicate, has previously spoken about being a "prisoner" in his own body and he has been campaigning for a change in the law.
In July he wrote an open letter to MSPs and he also has a blog and has written a book.
His wife told BBC Scotland: "I think it would have been easier for me if we could have had the facility here in order for Richard to be able to choose the time and place of his death and it would be familiar surroundings. It adds another layer on to what is already a complex grief process.
"I have no idea what I am going to be like after Friday."
Those who argue against a change in the law say it would undermine palliative care and the risks are too high.
Dr Stuart Weir, national director at Christian charity CARE for Scotland, said: "We believe this report muddies the waters by suggesting palliative care and assisted suicide are two sides of the same coin.
"The truth is that legalising assisted suicide goes right against the ethos of palliative care and in fact would undermine it."
He said there was a debate to be had about the provision of palliative care across Scotland, but that was "a separate conversation to whether we should legalise something as dangerous as assisted suicide, with all the consequences of doing so".
"The best safeguard against abuse, coercion, exploitation and the pressure that would inevitably be put on patients and palliative care doctors especially if assisted suicide was legalised is the current law," he added.
'Dignity at the end'
Mr Selley will make his final journey on Friday with Elaine by his side.
"In many ways it is harder for Elaine than me," he said.
She added: "I think I'm having to be as selfless as I have ever been to allow this to happen and to support this, because if I could spend an extra day with Richard, I would spend an extra day with Richard.
"For him, I know it's what he wants. I'm supporting him to make this choice and have this dignity at the end of his life. I also know he is tired and his body is failing."
He said: "It would be good to be famous for something more cheerful but in death I hope I can bring change for many in my position in the future."