candidates leaving 14 dead and a third of Iraq's provinces - all of them mainly Sunni Arab or Kurdish - not even voting.
The election is seen as a gauge of the popularity of Prime Minister Nuri al-Maliki's Shiite-led government ahead of a general election next year, but major issues affecting voters such as poor public services and rampant corruption have largely been ignored during the campaign.
"I don't believe this election will provide a magic solution for the problems of Iraqis, and the problems in the country," said Ihsan al-Shammari, a politics professor at Baghdad University.
But, he said, a well-run vote with a high turnout could bolster Iraqi belief in democracy a decade after US-led forces ousted now-executed dictator Saddam Hussein.
"The results will show the popularity of the various parties and, because of this, we see that party leaders are themselves leading campaigns," Shammari said.
Polls opened about 7:00am (4am GMT) and are to close at 5:00pm (2pm GMT).
The elections are the first since parliamentary polls in March 2010 and also the first since US troops withdrew from Iraq in December 2011.
An estimated 13.8 million Iraqis are eligible to vote for more than 8,000 candidates, with 378 seats being contested.
But the lead-up to the vote was blighted by a spike in violence that left more than 100 people dead in the past week, and 14 election candidates killed since campaigning began.
Six of Iraq's 18 provinces are not participating - two because authorities say security cannot be ensured, and four because of various political disagreements.
Those two factors have led diplomats to worry about the credibility of the election, as they could result in low voter turnout, leading to results that are not representative or broadly accepted.
Security was tight on Saturday, with only approved vehicles allowed on the streets and concertina wire closing off areas around polling stations.
"We will use all of our forces in the interior and defence ministries to control the situation," said interior ministry spokesman brigadier general Saad Maan.
Iraqi forces were responsible for security on polling day, the first time they have been in charge without support from American or other international forces during elections since Saddam was toppled.
While violence in Iraq has fallen significantly since the height of its sectarian war, it still faces significant security challenges, mainly from Sunni militants linked to Al-Qaeda who launch attacks in a bid to undermine confidence in the Shiite-led government.
Provincial councils are responsible for nominating governors who take charge of the provinces' administration, finances and reconstruction projects, and have sway over key local issues such as sewerage and other services.
But while several contentious issues fall under the purview of the provinces, campaigning in Iraq is rarely on ideological or policy lines. Candidates generally appeal to voters on the basis of shared sectarian, ethnic or tribal identities.
As a result, many key concerns, such as poor public services, widespread corruption and high unemployment, have gone largely unaddressed.