The 81-year-old Berlusconi voted in his native Milan, where he was confronted by a half-naked activist.
"Berlusconi, your time is over," was written on the bare breasts of the woman who climbed on a table inside a polling station. "My time is over? Yes, that's right and the queue is here," Berlusconi quipped, as reported by news agency Ansa.
Berlusconi leads a rightist coalition seen as the frontrunner, but the Five Star Movement, predicted to do well in the poorer south and among disaffected young voters, could stop it from winning a parliamentary majority.
Polling has now closed with final results due tonight NZT.
"The fact that Berlusconi is still here shows how far our politics has fallen," said one voter in Rome. "Whatever the outcome, it will turn out badly," said another. "We're all very worried."
The third main contender, a centre-left coalition based around the ruling Democratic Party (PD) and led by former Premier Matteo Renzi, is expected to face heavy defeat - but the PD could still hang on to power.
Most analysts are expecting a hung parliament, setting the stage for difficult government coalition talks.
One possibility is for Berlusconi and the PD to form a centrist grand coalition; another - which could spook Italy's EU partners and financial markets - is a M5S-led administration that potentially could include Berlusconi's far-right party ally, the League.
AP, DPA, AAP