Czechs are voting in a two-day general election in which the favourite is a populist billionaire who has campaigned on an anti-establishment platform.
Andrej Babis, 63, is estimated to be worth $4 billion (£3bn) making him the country’s second richest man.
His centrist ANO (Yes) party has a wide lead in the polls but is not expected to secure a majority.
Its current coalition partner, the centre-left Social Democrats (CSSD), is polling in second place.
Polls opened at 14:00 local time (12:00 GMT) and close at 22:00 (20:00 GMT). They will open again on Saturday morning and close in the afternoon.
Andrej Babis’s party, which has campaigned on an anti-establishment, anti-EU and anti-corruption basis, is predicted to win the biggest share of the vote.
Far-right and far-left parties are also predicted to make gains.
This will put Mr Babis, who has faced numerous scandals including a fraud indictment and accusations he was a communist-era police agent, in pole position to become prime minister as part of a coalition.
If his party secures a majority, it is not known who Mr Babis will seek to form a government with.
Currently, Social Democrat Bohuslav Sobotka heads a coalition formed after a 2013 snap election. This was triggered by the fall of the centre-right government of Petr Necas over a spying, sex and bribery scandal earlier in the year.
In May, Mr Sobotka submitted his government’s resignation because of a disagreement with Andrej Babis, who was serving as finance minister at the time.
He was unhappy about alleged unexplained business dealings involving Mr Babis.