Exit polls have shown that Italy is set for hung parliament after voters support right-leaning and populist parties.
Early Monday morning projections show that former prime minister Silvio Berlusconi's center-right coalition will take the most seats in the lower house of parliament, but will fall short of winning an absolute majority.
Polls show that Berlusconi's coalition will gain around 225-265 seats, which is below the 316 required for an absolute majority.
The 81-year-old ex-premier cannot hold public office due to a tax fraud conviction but has allied himself with the anti-immigrant League Party to be able to compete in the race.
Exit polls put the anti-establishment Five Star Movement in second place with about 30 percent of votes and 195-235 seats.
The country's ruling center-left Democratic Party comes in the third place with a projected 115-155 seats.
"The verdict in Italy is always the same: the country is in constant instability. Being ungovernable has become endemic," said Claudio Tito, columnist for La Repubblica.
The Five Star Movement, which was founded in 2009 by a web entrepreneur and a former comedian, has tapped into disillusionment with traditional parties.
"I voted for the right and Berlusconi in the past... but this time I'm voting Five Star Movement to be against the parties that have always stolen," said 24-year-old pastry chef Francesco Tagliavini at a polling station in Rome's Tor Marancia neighborhood.
"We hope something will change because until now things have been very bad," said Enzo Gallo.
"The middle class no longer exists, the poor are becoming poorer, the rich are becoming richer and there is no social justice," he added.
Polling stations opened at 07:00 local time (0600 GMT) and closed at 23:00 (2200 GMT) on Sunday, with more than 30 million people eligible to vote.