An eerie sense of calm has descended on Baghdad as shops, schools, banks and cafes have closed and most of the city's seven million residents are staying at home.
A five-day holiday began on Tuesday as part of security
steps brought in before Iraqis go to the polls. All of Iraq's borders have been closed.
The 15.5 million people elgible to vote will elect 275 parliamentary deputies, each with a four-year mandate.
The vote is the latest attempt to further Iraq's transition to a full democracy and eventually allow US-led forces to leave.
Iraqi expatriates in 15 countries across the world are already casting their ballots in a three-day process that began on Tuesday.
Voters in Iraq's hospitals and prisons were the first to cast their ballot papers on Monday.
Many Iraqis and foreign diplomats hope that the first full-term
legislature since the 2003 invasion will draw disaffected Sunni Arabs back into politics.
The Sunni minority boycotted elections in January but more than 1000 Sunni clerics have pressed members of their community to vote this week. They hope to increase their chances of playing kingmaker in the new government.
Iraqi military personnel search
civilians on a street in Basra
However, a functioning government could take some time to be achieved, according to one senior US lawmaker.
Following a White House briefing on the vote, Senator Richard Lugar said: "The briefers cautioned that given the multiplicity of parties and interests, solidifying a parliamentary government will not be instantaneous.
"Under some scenarios, the selection of ministers might not be finalised until April."
However, violence is still a major threat to the elections.
Four US soldiers, a police commando and a businessman working with the US army were killed on Tuesday.
In the heavily damaged western city of Ramadi, a leading local electoral candidate in Anbar province, Mizhar al-Dulaimi, was also killed on Tuesday. He is the latest of the political
Violence has plagued the weeks
of election campaigning
assassinations that have marred campaigning.
Al-Qaida has warned people in Ramadi not to vote and threatened to kill those who take part in the election.
In Mosul, two Iraqi policemen died and two were wounded on Wednesday when a bomb exploded alongside their patrol, police said.
Meanwhile, the Interior Ministry has strongly denied earlier media reports that a tanker truck filled with thousands of
blank ballots had been confiscated in a town near the
A stement simply read , "This report is untrue and it aims to affect the election process."