Act MP Heather Roy is calling time on her parliamentary career.

Mrs Roy, 47, will retire at the November 26 election after nine years in Parliament, during which time she rose to be deputy leader of her party and a minister before being dumped from the posts by her party last August. The move was led by then ACT leader Rodney Hide -- who has since been rolled by former National leader Don Brash.

"The big low point was last year when I was dumped. And pretty unceremoniously," Mrs Roy said.

"In politics they say it's not being stabbed from the back you have to worry about, it's being stabbed from the front. It was pretty torrid and tough. But it is politics."

The time was right to leave now and, while it would have been the easy option last August, she was too worried about the state of the party.

She planned to spend more time with her husband, Duncan, and five children aged 15-23, and said she bore little animosity towards Mr Hide.

"You just have to move on with life."