The first-round presidential polls in the Caribbean nation, which is also holding second-round legislative elections and voting for local officials, are unfolding in a climate of uncertainty.
Two people were killed in sporadic violence during first-round legislative polls in August, and some had feared the threat of renewed violence could keep turnout low on today.
Police will deploy 10,000 officers, backed by 5,000 from the UN peacekeeping force MINUSTAH.
"I came here to vote today because I think the situation in my country is tragic, and it has been for decades," said a man casting his ballot in the capital Port-au-Prince, who only gave his first name, Joseph.
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Results in the presidential election are not however expected before early November.
Former Brazilian foreign minister Celso Amorim, the head of a 125-strong election observer mission from the Organization of American States, said that in the early hours, things were running slowly but smoothly.
The elections come nearly five years after President Michel Martelly came to power in a country that has failed to find democratic stability since the end of the 30-year Duvalier dictatorship in 1986.
The pop singer and political novice assumed office in 2011, the year after a catastrophic earthquake killed more than 200,000, flattened most buildings in the capital and left hundreds of thousands living on the streets.
Five years on, more than 85,000 people still live in makeshift camps, according to Amnesty International.
Fifty-four candidates are running for Haiti's highest office and a chance to lift the destitute nation out of its systemic poverty.
But that abundance of hopefuls is not a sign of democratic health.