The debate is scheduled to begin at 7.30pm on Wednesday night, with the House of Assembly to consider a number of amendments to the original bill which comfortably passed the upper house last month.

If those amendments are all rejected, it could proceed to a final vote.

But if some amendments are agreed to, the legislation will return to the Legislative Council for final approval.

If it passes, SA will become the fourth state to legalise voluntary assisted dying laws after Victoria, Western Australia and Tasmania.

The original bill included 68 safeguards and a provision that people wishing to end their lives must be resident in SA for at least 12 months and at least 18 years old.

It requires patients to show they have decision-making capacity and are capable of informed consent, and to undergo an assessment by two independent medical practitioners not related to the applicant.

They must have their request verified by two independent witnesses and be experiencing intolerable suffering that cannot be relieved.

A terminal diagnosis and a life expectancy of less than six months, or 12 months for a person with a neurodegenerative disease, must also be confirmed.

Most concerns among MPs about the bill have related to coercion and pressure, especially on elderly people.

The legislation has the support of Premier Steven Marshall but all MPs are free to vote according to their conscience.

The Voluntary Assisted Dying SA group said Wednesday's vote was "an opportunity for our MPs to change the course of history".

Australian Associated Press