A tight race is expected between Xiomara Castro, Nasry Asfura and incumbent President Juan Orlando Hernandez.
Polls have opened in Honduras to elect a new president to replace Juan Orlando Hernandez, a controversial figure accused of drug trafficking in the United States.
"I call on everyone to proceed with this process in peace, calm, without fear and without violence," said National Electoral Council president Kelvin Aguirre on Sunday, following concerns over potential violence.
More than five million people are registered to vote in what is expected to be a tight race.
Leftist opposition candidate Xiomara Castro led opinion polls last month, but the ruling right-wing National Party (PN) - whose candidate is charismatic Tegucigalpa mayor Nasry Asfura - has had the benefit of better campaign organisation and resources.
Opposition fears of a rigged poll and reports of pre-election intimidation have led to tension.
Four years ago, Hernandez won an unconstitutional second successive term amid cries of fraud from the opposition and international observers.
Hernandez's re-election sparked a widespread month-long protest, with the subsequent government crackdown leaving more than 30 people dead.
The concerns come for a country already ravaged by violent gangs, drug trafficking and hurricanes, in which 59 percent of the population of 10 million live in poverty.
Corruption and drug-trafficking scandals have also engulfed Hernandez and many of his inner circle in recent years, including Asfura.
The crucial moment will come three hours after polls close at 5:00 pm, when the National Electoral Council (CNE) is due to announce early results, Gustavo Irias, executive director of the Center for Democracy Studies said.