The National Party MP for Rangitata, Jo Goodhew, will quit politics at this year's general election.
She was dumped as a minister in December when incoming Prime Minister Bill English appointed his Cabinet.
Throughout her political career, Ms Goodhew has held numerous ministerial portfolios including Minister for Women, Food Safety and Senior Citizens. She was first elected to Parliament in 2005.
In a statement, she said she had time over the summer break to think about her future.
"I'd like to thank the people of the Rangitata electorate for their incredible support ... I intend to remain 100 percent committed as their MP until the election."