Auckland's Mt Albert voters are going to the ballot boxes to decide who their next MP will be, and they have 13 candidates to choose from.
The seat is vacant after David Shearer, who held it for Labour, resigned from Parliament to take up a peacekeeping role with the UN in Sudan.
Labour's candidate is Jacinda Ardern, currently a list MP.
The Green Party is contesting the by-election and its candidate is also a current list MP, Julie Anne Genter.
National is not fielding a candidate, which makes Labour and the Greens the only parliamentary parties in the contest.
The other candidates are independents or representatives of small parties that don't have any MPs.
The booths open at 9am on Saturday and close at 7pm.
The Electoral Commission expects to have 50 percent of the votes counted by 9pm and a final result by 10pm.
There are just over 45,000 voters enrolled in Mt Albert.
More than 3000 advance votes have been cast.
The candidates are:
- Amos Adam (independent)
- Jacinda Ardern (Labour)
- Dale Arthur (Independent)
- Penny Bright (Independent)
- Patrick Brown (Communist League)
- Joe Carolan (Socialist - People Before Profit)
- Julie Anne Genter (Green)
- Abe Gray (The Cannabis Party)
- Geoff Simmons (The Opportunities Party)
- Simon Smythe (NAP)
- Vin Tomar (New Zealand People's Party)
- Anthony Van Den Heuvel (Human Rights Party)
- Peter Wakeman (Independent)