Italians are voting in one of the most uncertain elections in years and one that could determine if Italy will succumb to the populist, eurosceptic and far-right sentiment that has swept through Europe.
The campaign has been marked by the prime-time airing of neo-fascist rhetoric and anti-migrant violence that culminated in a shooting spree last month against six Africans.
While the centre-right coalition that capitalised on the anti-migrant sentiment led the polls, analysts predict the likeliest outcome is a hung parliament.
That will necessitate days and weeks of haggling to come up with a coalition government that can win confidence votes in Parliament.
Just which parties coalesce from among the three main blocs - the centre-right coalition, centre-left coalition and the anti-establishment 5-Star Movement - will determine Italy's course.
"Basically it is very likely that, at the end of the day, none of these three groups will have an absolute majority and they will be forced to start talking to each other and see how to put together a coalition government," said Franco Pavoncello, dean of the John Cabot University in Rome.
More than 46 million Italians were eligible to vote from 7am to 11pm, including Italians abroad who already mailed in ballots.
Exit polls were expected after polls closed, projections sometime thereafter and consolidated results on Monday.
Some polling stations remained closed in Palermo hours into election day because the wrong ballots were delivered and 200,000 new ones had to be reprinted overnight.
The outgoing Senate president, Pietro Grasso, complained that such delays were "unacceptable" and that he hoped they would not discourage turnout.
In Rome, meanwhile, some early voters said the ballots were confusing and the process to cast them - which for the first time requires an anti-fraud check by polling authorities - too time-consuming.
With unemployment at 10.8% and economic growth in the eurozone's third-largest economy lagging behind the average, many Italians have all but given up hope for change.
Polls indicated a third had not decided or were not even sure they would vote.
Analysts predict the only coalition with a shot of reaching an absolute majority is the centre-right coalition anchored by ex-premier Silvio Berlusconi's Forza Italia party.
The coalition includes the anti-migrant League and the nationalistic, neo-fascist-rooted Brothers of Italy party.
Mr Berlusconi, 81, cannot run for office because of a tax fraud conviction, but he has selected European Parliament President Antonio Tajani, considered a pro-European moderate, as his pick if the centre-right is asked to form a government.