Chileans are voting in a runoff presidential election between a former political prisoner and a billionaire businessman that could result in Chile's first female president.
About 8.2 million people are eligible to vote in the contest between Socialist Michelle Bachelet and Sebastian Pinera, the candidate of a rightist alliance.
Recent polls indicate that Bachelet leads Pinera by at least five percentage points in the contest to succeed outgoing President Ricardo Lagos.
Bachelet won Chile's first round of elections in December with 46 percent of the vote, falling short of the 50 percent needed to avoid a runoff.
The next president inherits an economy that has surged in part because of soaring prices for copper, which is Chile's top export.