As many predicted, civil society in Greece has broken down as a result of the harsh and painful austerity measures necessary to enact if the country was to receive its bailout money from the EU.
Dozens of buildings have been torched in the aftermath of the vote.
State television reported the violence spread to the tourist islands of Corfu and Crete, the northern city of Thessaloniki and towns in central Greece. Shops were looted in the capital where police said 34 buildings were ablaze.
Prime Minister Lucas Papademos denounced the worst breakdown of order since 2008 when violence gripped Greece for weeks after police shot a 15-year-old schoolboy.
Papademos told lawmakers shortly before they voted that they would be gravely mistaken if they rejected the package that demands deep pay, pension and job cuts, as this would threaten Greece's place in the European mainstream.
"It would be a huge historical injustice if the country from which European culture sprang ... reached bankruptcy and was led, due to one more mistake, to national isolation and national despair," he said.
The chaos outside parliament showed how tough it will be to implement the measures. A Reuters photographer saw buildings in Athens engulfed in flames and huge plumes of smoke rose in the night sky.
"We are facing destruction. Our country, our home, has become ripe for burning, the centre of Athens is in flames. We cannot allow populism to burn our country down," conservative lawmaker Costis Hatzidakis told parliament.
The air in Syntagma Square outside parliament was thick with tear gas as riot police fought running battles with youths who smashed marble balustrades and hurled stones and petrol bombs.
Terrified Greeks and tourists fled the rock-strewn streets and the clouds of stinging gas, cramming into hotel lobbies for shelter as lines of riot police.
Is there an alternative to austerity? Some on the left have proposed forgiving Greece her debts, nationalizing the banks, drastically cutting the defense budget, increasing taxes on the wealthy, and increasing wages to help ordinary Greeks get out of debt, thus spurring economic activity. None of this addresses the primary problem; the Greek government spends much more than it takes in. And for the last two years, Germany and France have subsidized Greek workers and pensioneers by agreeing to the first bailout regime that was designed to grow the country out of its troubles. It didn't work.
The two EU powerhouses are through with that. Greece must pay its own way or be kicked out of the euro zone. And if the rioters don't like austerity, they aren't going to like depression very much either.