The 79-year-old, who has had ongoing heart problems and uses a pacemaker, was taken to the San Raffaele Hospital in his birth city of Milan, the hospital's press office told CNN Monday, giving no details on his condition.
Berlusconi is a stalwart in Italian politics, having led the country as prime minister three times between 1994 and 2011. During one term, he resigned and was sworn back in three days later.
A former cruise-ship crooner turned media tycoon and politician, Berlusconi is one of the most colorful and controversial figures in Italy's lively history of politics. He has for years slipped in and out of Italian courts, entangled in fraud, corruption and sex scandals.
His pacemaker was fitted after a fainting episode while delivering a speech at a rally in 2006, a dramatic scene broadcast live all over the country.
Nonetheless, the maverick leader rebounded and was re-elected in 2008, calling himself the "the Jesus Christ of Italian politics."
Berlusconi, no stranger to headlines even when out of office, found himself back in hot water when accusations were made that he had paid for sex with a teenager
in "bunga bunga" sex parties thrown at his luxurious Milan home in 2010, when he served as prime minister.
"Ruby the Heartstealer" was the stage name for Karima El Mahroug, a former nightclub dancer who was 17 when she attended Berlusconi's parties.
Berlusconi was convicted of sex with a minor and abuse of power, but those convictions were overturned by a higher court. He has always denied that he had sex with El Mahroug, but admitted to paying her 57,000 euros (about $65,000) after she attended his soirees.
Political commentators have drawn comparisons between Berlusconi and Donald Trump, the presumptive U.S. Republican nominee for president, because of their authoritarian style and comments that many view as sexist.
Berlusconi famously once said that Italy was a great country to invest in, in part because "we have beautiful secretaries... superb girls."
Despite being convicted for tax fraud and bribery, the leader has managed to evade prison throughout his career. In one case he was ordered to perform a year's community service in a home for the elderly while in another, the statute of limitations expired, meaning he did not have to serve the prescribed jail term.
Forbes ranks Berlusconi
188th on its list of the world's billionaires, with a net worth of $6.2 billion.
His business empire owns football club AC Milan. He is reportedly trying to sell his majority stake
in the club to a Chinese consortium.