The election is expected to be a three-way race between incumbent Jose Ramos Horta, former military chief Taur Matan Ruak and former parliamentary speaker Francisco "Lu-Olo" Guetteres.
The president's role is largely ceremonial, but he has the potential to help unify Asia's newest and poorest nation, which is still recovering from a bloody break for independence from Indonesia a decade ago.
Its transition to democracy has at times been rocky.
Leaders have battled massive poverty, social unrest and bitter disputes between soldiers and police that
-- just a few years ago -- left dozens dead and resulted in widespread looting, arson and gang warfare.
With the future of the nation in doubt, U.N. and Australian troops were deployed to restore order. They are scheduled to pull out by the year's end.
More than 600,000 of the country's 1.1 million people were expected to vote Saturday.
Twelve candidates are on the ballot. If no one wins a 51 percent majority, the two top vote-getters will move on to a second and final round next month.