The alarm was sounded after objects which appeared to be bullets showed up on an x-ray of a letter addressed to the media magnate at his Arcore villa near Milan, and police and a decontamination unit were called to the scene.
It was not clear whether there was a note inside the envelope, the reports said.
The scare came days after an unemployed man shot and wounded two policemen outside government headquarters while Italy's new cabinet was being sworn in just a kilometre away.
While one was shot in the leg, the other suffered a serious injury to the neck and doctors have said he risks paralysis. Unemployment is high in the recession-hit country and the coalition government has promised to act fast to tackle social ills amid rising tension and anti-establishment feeling.
Berlusconi, who was counted out by critics after his government fell at the end of 2011, has enjoyed a recent surge in popularity and is credited by some with the power to topple the new government if the centre-right does not get its way on key issues.