Italy's highly fragmented party system made it hard to identify an overall trend, but the results were generally seen as a defeat for Italian Prime Minister Silvio Berlusconi and a victory for the centre-left opposition coalition identified with Romano Prodi, who was President of the European Commission until 2004, and was widely expected to re-enter Italian politics at the next election.

While the Olive Tree's performance was not as phenomenal as it had hoped, the test indicated a somewhat reduced support for the centre-right coalition.

Italian regions were united in 5 constituencies, each electing a group of deputies.

At national level, seats were divided between party lists using the largest remainder method with Hare quota.

All seats gained by each party were automatically distributed to their local open lists and their most voted candidates.