Kathleen Whelan knows more than most about the pain, suffering and indignity that can accompany the end of a person's life.

The Sydney resident spent her career working as a registered nurse, and saw many patients in their final days.

But it is the memory of her beloved sister Denise Wilson dying in an agony she believes could have been prevented, which is the force behind her fight to have voluntary assisted dying laws passed in NSW.

"Dying with dignity is a voluntary thing, it's your choice," Mrs Whelan said.

"If the law is passed, you will have the ability to take it - it's not something that will be forced onto you."

Queensland recently passed voluntary assisted dying laws, leaving NSW as the only Australian state still lagging behind.

"The Bill sets out a legal process for people who are suffering and dying from an advanced and progressive life-limiting condition the right to choose the timing and circumstances of their death," the Queensland Health website states.

"There are strict criteria for who will be eligible to access voluntary assisted dying."

Mrs Whelan said she was "ecstatic" to see our northern neighbour approve voluntary assisted dying laws.

"I'm very happy, but now NSW is the only state left," the 70-year-old said.

"We're not talking about people walking along the street being able to just go and die.

"We're talking about people who are going to die anyway - they can just die a little nicer.

"I've seen a lot of people at the end of their lives, and sometimes it's nice, but too many times it's the opposite."

Mrs Whelan said she had a "terrible experience" caring for her sister during her final days.

Denise had breast cancer and aggressive tumours which made simply existing unbearable.

"My sister had a terrible death," Mrs Whelan said.

"She begged me to end her life, and I couldn't do that for her.

"The memory of her last days were horrific. It wasn't just the pain, it was the lack of dignity.

"She started to smell before she died and she would have been horrified to know that we had to put a purifier in her room to try and manage the odour.

"I used to have to shower her and she would scream all the way through it. It broke my heart.

"In all my years of nursing, I'd never seen anyone suffer so badly."

Denise died 11 years ago, but the trauma of her death has never left Mrs Whelan and she doesn't want anyone else to be forced to suffer the same fate.

Mrs Whelan is encouraging everyone to reach out to their local MPs and push for NSW to pass voluntary assisted dying laws in line with Australia's five other states.

Dying with Dignity NSW president Penny Hackett said COVID had delayed the progress of the Bill in NSW.

"COVID-19 has stopped a lot of things, but it hasn't stopped people being diagnosed with terminal illnesses or experiencing intolerable pain and suffering from that illness," she said.

"Every day that NSW Parliament doesn't pass this important legislation, terminally ill people will continue to suffer unbearably at the end of their life."