Residents in Istanbul are casting their votes in the re-run of Istanbul's mayoral election that was annulled over election irregularities.
Opposition Republican People's Party (CHP) candidate had handed President Tayyip Erdogan's AK Party (AKP) a rare electoral defeat in March with a narrow majority.
But after weeks of AKP appeals, Turkey's High Election Board in May annulled the vote citing irregularities.
Ekrem Imamoglu, who had won by 13,000 votes, has vowed to "battle for democracy" and polls say he is likely to beat former Prime Minister Binali Yildirim for a second time.