ACT MP Sir Roger Douglas says he will retire from politics at November's general election.
Sir Roger entered Parliament in 1969 as the Labour Party MP for Manukau.
He is best known for his role in the economic restructuring undertaken by the fourth Labour Government in the 1980s.
Sir Roger retired from Parliament in 1990 but returned as an ACT Party list MP at the 2008 election.
He came under criticism in 2009 for spending $44,000 on air travel in the first six months of that year.
Sir Roger has been part of an ACT caucus that has seen significant tensions, most notably when Heather Roy was ousted as deputy leader of the party.
Sir Roger supported Ms Roy through that process but would not get directly involved in the infighting.
He says he will be 74 in November and it is time to bow out of politics altogether.
Sir Roger says he would have liked to have achieved more during this parliamentary term but he plans to finish a book before the election, so at least his ideas are on the table.
He says he plans to spend more time with his grandchildren and help his daughter set up her new business.