The migrants, mostly from Africa, usually embark in Libya or Tunisia in an exodus increased by political turmoil in North Africa and the Syrian civil war.
About 325 migrants, among them 64 women and four children, were sighted on Tuesday morning on a fishing boat off the coast of Porto Empedocle on Sicily's southern coast. They were transferred to coastguard boats and taken to shore, police said.
Another 230 were brought ashore after they were intercepted off the coast of the island of Lampedusa, Italy's most southern point, while a group of about 110 reached the shores of Siracusa, in Sicily. Tuesday's arrivals followed those of about 400 migrants on Monday afternoon.
The flow of migrant boats has been intense this summer, but roughly in line with the past two years. Almost 9,000 immigrants reached Italy by boat between July 1 and August 10, the Interior Ministry said last week.
In the past 12 months, more than 24,000 have come, compared with more than 17,000 in the same period a year earlier, and almost 25,000 in the 12 months before that, the ministry said.
The flood of migrants is drawn by the prospect of finding work in the European Union and many do not remain in Italy.
Illegal migrants intercepted by Italian authorities are taken to state-run immigration centers. Some leave the often lightly guarded buildings to seek work, and those who remain and cannot prove that they are political refugees can be sent home.
Some of the migrants who arrived on Tuesday said they were from Syria, where the civil war has been raging for two years.
