The young women had the slogan "Basta Berlusconi" (Enough with Berlusconi) scrawled on their backs.
They were quickly detained by police and dragged away screaming in a chaotic scene as ordinary people also queued to vote at the school.
Police struggled to put their jackets and handcuffs on the women as they writhed in the snow.
The protesters broke through a line of journalists outside the polling station and jumped over some tables toward Mr Berlusconi but did not reach him.
The scandal-tainted ex-prime minister is leading a centre-right coalition in the election and polls indicate he will come second to the centre-left.
The elections are Italy's first since billionaire tycoon Berlusconi was ousted in 2011 during a wave of financial market panic and replaced by former top European commissioner Mario Monti.
The most likely winner is the Democratic Party and its leader Pier Luigi Bersani, who says he will stick to reforms but also do more for growth as Italy endures its longest recession in 20 years.
"I am voting for the Democratic Party. I don't want us to end up like Greece," said Alessandro, a 63-year-old manager, as he cast his ballot in Milan.
But Mr Berlusconi, a three-time prime minister who is also a defendant in two trials for tax fraud and having sex with an underage prostitute, could come a close second.
"There's a lot of confusion in these elections. I'm voting Berlusconi. I know he has his defects but he's the best," said Maria Teresa Gottardi, 65.
In third place, according to the polls, could be a new protest party led by comedian turned activist Beppe Grillo, who has channelled growing social discontent and anger at traditional politicians.
Polling stations close on Monday morning (AEDT) and open again for a second day of voting later that evening.
Officials have called on Italians to vote amid fears that general disenchantment with politics could mean a much lower turnout than usual.
Forty-seven million Italians are eligible to vote.
Opinion polls indicate the result may not give Mr Bersani alone a strong enough majority to rule and he may have to seek an alliance with Mr Monti, which could bring the economics professor back into government.
A coalition between Mr Monti and Mr Bersani would not be simple because of the differences between the free marketeer Monti and a small far-left party that is already in coalition with Mr Bersani.
Mr Berlusconi will also continue to be a powerful force. He has risen sharply in the polls with a promise to reimburse an unpopular property tax.
He has also won votes by blaming a "hegemonic" Germany for Italy's woes.
The candidates were supposed to stay silent on the eve of the vote but Mr Berlusconi apparently broke the rules by speaking to journalists.
In an interview with Greek television that was reported by Italian media, he said: "I contradicted the lords of austerity who are now trying to get rid of me."
He said Mr Monti was "subservient and always on his knees in front of Mrs Merkel (German chancellor Angela Merkel) and now she does not want to lose him".
"I would give her a run for her money," he said.
Italy is the euro area's third largest economy after Germany and France and a major exporter.
While its debt is sky high at around 120.1 per cent of its gross domestic product (GDP) - second only to Greece - its public deficit is under control.