Polish prime minister Ewa Kopacz has conceded defeat after an exit poll showed that her pro-European Civic Platform party faced a decisive defeat by the right-wing Law and Justice party.
The exit poll by Ipsos shows that Law and Justice won 39.1% of Sunday's parliamentary vote.
If confirmed by official results, which are expected on Monday, that would give Law and Justice 242 seats in the 460-seat lower house of parliament, allowing it to govern alone.
That would mark the best showing yet for the party in a parliamentary election.
According to the exit poll, Civic Platform would get 133 seats and only three other parties would make it into parliament: a party led by rock star Pawel Kukiz, a new pro-business party named Modern Poland and the Polish Peasants Party.