The second and final round of voting for a new mayor is taking place in Argentina's capital, Buenos Aires.
Mauricio Macri has a clear lead
Right-wing businessman Mauricio Macri is expected to beat Daniel Filmus, who is backed by President Nestor Kirchner.
Mr Macri won the first round of the polls on 3 June, but he failed to get the 50% needed for an outright victory.
The poll comes just four months before presidential elections and gives an indication of how President Kirchner's government is doing.
Buenos Aires dominates Argentina, so the battle for one of the most influential posts in the country's politics has been hard-fought, the BBC's Daniel Schweimler says.
Crime and taxes
Mr Macri is best-known as the president of Boca Juniors football club in the football-mad nation.
Recent opinion polls suggest a comfortable victory for Mr Macri, our correspondent in Buenos Aires says.
Last Wednesday, Mr Macri received a timely boost when the team won Latin America's most prestigious club competition - the Copa Libertadores.
Mr Filmus - who is Argentina's education minister - is the left-of-centre government candidate. He is strongly backed by President Kirchner.
Both contenders have focused on crime and taxes during their election campaigns.
The city is enjoying an economic boom but the rapid growth is also bringing problems such as crime and pollution, our correspondent says.
The incumbent mayor Jorge Telerman, who got the job last year by default when his boss was sacked, is out of the race, finishing in third place.