Plans of the Italian Government to open the taxi service to more competition caused the large demonstration of cab drivers. They walked off their jobs Tuesday to protest.
About 25,000 cabs - out of an estimated total of about 30,000 - were expected to take part in the strike, with thousands expected at a demonstration in central Rome, said the head of a taxi association, Maurizio Longo.
The hours were varying from city to city. In Rome and Milan the walkout was due to run from 8 a.m. until 10 p.m. (0600 GMT to 2000 GMT), Longo said.
Last year, the cab drivers staged a massive protest that paralyzed Rome and left residents and tourists with no cabs for days.
The government wants to liberalize taxi licensing, as part of a wider package of measures aimed at injecting more competition into various sectors of the economy. Supporters say that consumers would ultimately benefit from more taxis, but the drivers are against the measures and fear increased competition after spending tens of thousands of euros (dollars) on purchasing their taxi license.
Several strikes have hit Italy recently, including by doctors, Alitalia flight attendants and local transport workers in Milan.