Voting got under way on Sunday morning in Brazil, where President Luiz Inacio Lula da Silva was confident of winning a second term.
Voting stations opened at 4.30 pm and balloting was scheduled to conclude nine hours later.
Opinion polls ahead of the election gave Lula, 60, a self-styled champion of the poor, a commanding lead over former Sao Paulo governor Geraldo Alckmin, 53.
The key question was whether Lula would be able to clear the 50 percent hurdle to get immediate victory and avert going to a second round.
About 126 million eligible voters were called to cast their ballots in the presidential, gubernatorial and congressional elections.