Over the past four years she consistently championed the cause, arguing that people with progressive, degenerative conditions should be able to end their lives if they wanted and that if they needed help, those who offered assistance should not fear prosecution.
She brought two Member's Bills before Holyrood. The first was convincingly defeated in 2010 by 85 votes to 16. However, she returned with a new bill last year, designed to include more safeguards against abuse, after getting the necessary 18 signatures from other MSPs.
Speaking when she launched the second Bill, she said: "I decided as soon as we lost the last one that I had to get a better one and reintroduce it, because so many people think this is the right thing to do for people who have a progressive, degenerative condition who are facing a less than dignified end.
"And people who are terminally ill, if they want to go just a bit sooner, they should be able to choose to do so without making anyone subject to prosecution."
MSPs will once again be allowed to vote according to conscience rather than along party lines and Ms MacDonald said just weeks ago that she was confident of success,
Green MSP for Glasgow Patrick Harvie said he felt "deeply privileged" to have worked with Ms MacDonald on the legislation while the Humanist Society Scotland said it would continue to campaign for the Bill in her memory.
During her first bid to legalise assisted suicide, the legislation proposed anyone aged over 16 could request help to die so long as they have been diagnosed as terminally ill or permanently physically incapacitated and find life intolerable.
It came in for criticism from some campaigners who said the Bill inappropriately targeted disabled people, although Ms MacDonald disputed the claim.
The second Bill, on which it is anticipated MSPs will vote next year, this time applies only to people with a terminal or life-shortening illness. They would have to make three separate declarations to doctors, with set time delays including a 14-day "cooling off" period. Doctors would then supply a licensed facilitator, who would oversees the process, and write a prescription to enable assisted suicide to take place.
Last month, several leading doctors wrote to The Herald in support of the legislation, a development Ms MacDonald said had left her "cock-a-hoop".
Speaking to this newspaper, she said: "We have a very good Bill. I have a feeling there is much more support in Parliament this time. I am sure it is an indication that opinion across society is moving towards supporting assisted death in strictly defined cases. We are not saying anyone can ring the doctor and say, 'I've had enough, give me a jag', but some people can't have a peaceful death that all of us would want and have to undergo a horrible end of their life in great agony.
"If we have a group of people who are trained and supported to help a person bring their life to an end, and they have to abide by rules of doing this service and report themselves afterwards, I think we are pretty well covered."
However, as with many of the causes she strongly supported, it was controversial. She passionately defended her Bill days later after another group of doctors said that most in the profession were strongly opposed to the law change.
A spokesman for the Humanist Society Scotland (HSS) said: "Throughout her political career she represented her constituents, and the many causes in which she believed, with passion and dignity.
"The HSS supported her first attempt to make assisted suicide legal, back in 2010, and we will continue to campaign in her memory, but our thoughts are now with her family and friends."