Prominent American “right-to-die” advocate Brittany Maynard has chosen to end her life surrounded by friends and family.

The 29-year-old, who suffered from an aggressive type of brain cancer and was given six months to live, had been outspoken in the media about her decision to kill herself before her illness could get any worse.

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Prior to her death, she shared a message of farewell on her social media channels.

Brittany with her husband, Dan, visiting the Grand Canyon. Photo: AAP

“Goodbye to all my dear friends and family that I love. Today is the day I have chosen to pass away with dignity in the face of my terminal illness, this terrible brain cancer that has taken so much from me … but would have taken so much more,” she wrote.

“The world is a beautiful place, travel has been my greatest teacher, my close friends and folks are the greatest givers. I even have a ring of support around my bed as I type … Goodbye world. Spread good energy. Pay it forward!”

Maynard and her husband, who had just married when she was diagnosed, moved from their home in California to Oregon, one of a handful of US states with a “right-to-die” law.

A doctor could therefore prescribe her the medication she needed to end her own life, surrounded by her family in the bedroom she shares with her husband.

On Thursday, she had released a new video in which she said she might temporarily delay her death.

However, Ms Maynard decided she couldn’t wait any longer and died on Saturday in her Portland home.

Maynard has in recent weeks and months been working to tick off items on a “bucket list” of what she wants to do before she dies – including travelling to the Grand Canyon last week.

Readers seeking support and information about suicide prevention can contact Lifeline on 13 11 14 or Suicide Call Back Service 1300 659 46.