STORY: Voters get two voting slips - one for the Senate and one for the lower house. They can only put one cross on each slip, with that vote counted for both the first-past-the-post and proportional representation segments.
Every ballot paper has an anti-fraud segment that officials have to rip off before placing them into the ballot boxes.
After leaving the booth, the voter must hand the folded ballot papers to the polling station staff who must check that the anti-fraud code on the ballot paper matches the one assigned before voting.
Italy's first autumn national election in over a century was triggered by party infighting that brought down Prime Minister Mario Draghi's broad national unity government in July.
Polls close at 11.00 p.m. (2100GMT).