Iraqis are voting in the country's first parliamentary elections since the withdrawal of US troops three years ago.
Polling began at 07:00 local time (04:00 GMT) and close at 19:00.
Iraqis are going to polls despite threats from terrorist groups including the Islamic State of Iraq and the Levant (ISIL).
More than 9,000 candidates are competing for 328 parliamentary seats, BBC reported.
Prime Minister Nouri al-Maliki is hoping to win a third term in office amid a growing insurgency in the west of the country.
Iraq is experiencing its worst unrest since 2008, with 160 people killed in the last week alone.
More than 20 million Iraqis are eligible to vote, with almost 50,000 polling stations open across the country.
The government has temporarily closed the airport and the main roads in and out of the city in an attempt to reassure voters.
While it is difficult to predict the outcome of the poll, Maliki is still expected to be a pivotal figure in the coalition-building process which will follow the election.
His State of Law alliance, a Shia coalition, has largely avoided the fragmentation seen by other political blocs since the last election.
BA/BA