Tunisians were voting Sunday in an election seen as pivotal to establishing democracy in the cradle of the Arab Spring uprisings, with security forces deploying heavily to avert extremist attacks.
When polls opened at 7 am (0600 GMT), dozens of voters were already queueing outside one polling station in Marseille Street in central Tunis, an AFP correspondent reported.
The North African nation has been hailed as a beacon of hope compared with other chaos-hit countries like Libya and Egypt where regimes were also toppled.
But its transition has been tested at times by militant attacks and social unrest.
On the eve of the polls, Prime Minister Mehdi Jomaa warned of possible jihadist attacks aimed at disrupting the country's first post-revolution parliamentary election.
"We know that this will be a target (for jihadist groups) because it is unique in the region. It brings hope," Jomaa told AFP during an inspection of security forces east of Tunis.
"They know that the success of (this election) is a threat to them, not only in Tunisia but throughout the region."
On Friday, Tunisian police killed six suspected militants -- five of whom were women -- in a raid on a house in the outskirts of the capital.
A policeman was also killed in an earlier firefight with the suspects.
Up to 80,000 troops and police have been deployed in a bid to protect voters.
The country has flirted with disaster in recent years, particularly in 2013 when a rise in militant activity and the assassination of two opposition lawmakers threatened to derail Tunisia's path to democracy after its 2011 uprising that inspired the Arab Spring protests.
The revolt ousted veteran autocrat Zine El Abidine Ben Ali and ushered in a coalition government and interim president that won praise from the international community.
Several parties competing for seats in parliament are fronted by former regime officials.
Although they have publicly sought to distance themselves from the repression and intimidation practised under the ex-president, many voters who took part in the revolution are angered at the prospect of Ben Ali cadres returning to parliament.
Others accuse Islamist Ennahda -- Tunisia's largest party -- and its secular allies of failing to address people's needs as the economy remains weak and security incidents are on the rise.
"These politicians aren't worth a minute of my time. They are incompetent and have impoverished the people," said street vendor Bechir Bejaoui.
In spite of pockets of voter apathy, five million Tunisians are eligible to vote in a closely monitored election that interim president Moncef Marzouki has dubbed a "defining moment."
Sunday's vote pits Ennahda against secular rival Nidaa Tounes and an array of leftist and Islamist groups.
Ennahda leader Rachid Ghannouchi has predicted his party will improve on the 37 percent of the vote it won three years ago in an election to a constituent assembly, which drew up the post-Ben Ali constitution.
But Mohsen Marzouk of Nidaa Tounes said he expected his party and Ennahda to divide up 150 of the 217 seats in the new parliament.
"I believe parliament will be fragmented," he said.
Polls close at 6 pm (1700 GMT). Election officials have until Friday to announce the results.