Greece has became the sixth European Union member to approve the EU constitution when its parliament overwhelmingly voted in favour of adopting it.
Both the ruling conservatives and the opposition socialists backed the treaty which was ratified with 268 votes in favour and 17 against it, 15 deputies abstained.
Greece had said it wanted to be among the first nations to ratify the treaty, aimed at streamlining the bloc which last year introduced ten new members.
European Commission President Jose Manuel Barroso had urged Greece ahead of the vote to send a strong signal of support for the treaty as a crucial constitution referendum in France looms in May.
"There will be a clear signal coming from the Greeks for the rest of the continent," Mr Barroso said yesterday during a brief visit to Athens. "The Greek citizens have shown their commitment to European integration."
Polls show EU founder member France could vote against the constitution in a May 29th referendum, potentially triggering a political crisis in the bloc.
The constitution needs to be ratified by all 25 EU member states to come into force. Apart from Greece, five other nations - Spain, Italy, Hungary, Lithuania and Slovenia - have so far ratified the treaty.