Chile vote: Childhood friends face off in presidential poll
Opinion polls give a big lead to Michelle Bachelet
Chile is going to the polls in presidential elections with Socialist candidate Michelle Bachelet predicted to become the first Chilean leader in more than 50 years to serve two terms.
Opinion polls give her a substantial lead over her nearest rival - right-wing candidate Evelyn Matthei.
But the election could still go to a second round in December.
The two candidates were childhood friends before they were divided by the Pinochet dictatorship.
Mrs Bachelet, a paediatrician by training, was Chile's first woman president between 2006 and 2010.
Opinion polls put her on just under 50% - not quite enough to avoid a run-off - but still 30 points more than Mrs Matthei.
Mrs Bachelet, who leads an alliance of her Socialist Party, Christian Democrats and Communists, has campaigned on policies designed to reduce the gap between rich and poor.
Chile is one of the richest countries in Latin America, but millions have staged protests over the past few years to push for a wider distribution of wealth and better education.
Mrs Bachelet, 62, wants to increase taxes to offer free university education and reform political and economic structures dating from the dictatorship of Augusto Pinochet, who ruled from 1973 to 1990.
Her manifesto this time is much more radical than before, says the BBC's Gideon Long in Santiago.
"We have to win broadly, we're in this game for the first round because we have so much to do," Mrs Bachelet told a campaign rally on Thursday.
Evelyn Matthei, 60, has called for a continuation of the policies of outgoing President Sebastian Pinera, asserting that Chileans are "better off" now than when he came to power four years ago.
She and Mrs Bachelet are the daughters of generals who found themselves on opposite sides of the political divide once General Pinochet came to power.
As children in the 1950s, they were neighbours and used to play together on the airbase where their fathers worked.
Under General Pinochet, Evelyn Matthei's father, Fernando, rose up the ranks to run a military school where Michelle Bachelet's father, Alberto, died of a heart attack as he was being tortured.
More than 13 million Chileans, more than two thirds of the population, are eligible to take part in the election. Polls open at 11:00 GMT.
Other candidates standing in the election include an economist and relative newcomer to the political scene, Franco Parisi, and the film maker, Marco Enriquez Ominami.
The lower house of congress and half the senate are also being elected.