RTÉ.ie/Lisbon has complete results and live video/audio feeds of the Referendum.
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Irish voters have rejected the Lisbon Treaty.
With results in from all 43 constituencies, the Lisbon Treaty has been defeated by a margin of 53.4% to 46.6%.
A total of 752,451 people voted in favour of the treaty and 862,415 voted against.
Just 10 constituencies - Clare, Dublin South, Dublin South East, Dublin North, Dublin North Central, Dún Laoghaire, Kildare North, Laois Offaly, Carlow Kilkenny and Meath East - voted in favour of the Treaty.
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Tánaiste Mary Coughlan, Fine Gael leader Enda Kenny and former Taoiseach Bertie Ahern all failed to carry the vote in their own constituencies.
The result comes as a surprise to many in Europe, and was also a shock for political activists in Ireland.
Campaigners on both sides felt the Yes side had made up some ground in the last week - but that impression turned out to be wrong.
The margin of victory for the No side is similar to the first referendum on Nice - but on a much higher turnout.
In general, the picture is that working class and rural constituencies voted against, while middle class areas were in favour.
Just ten of the 43 constituencies voted in favour - compared to only two that were on the Yes side in Nice 1.
In regional terms, the result was closest in Dublin, where the No side won by 51% to 49%.
But the capital also had the widest margins. It had the constituency with the highest No vote (Dublin South West at just over 65%) and the constituency with the highest Yes vote (Dun Laoghaire with 63.5%).
The region with the highest No vote was Connacht/Ulster, where the No vote led by 57%.
Waterford was the first constituency to declare an official result - and it was unequivocal, rejecting Lisbon by 54-46.
This morning's tallies showed the strength of the No vote across the country, with just a handful of constituencies looking like they would vote Yes.
Each constituency counted its own votes separately, before sending the result to the Referendum Returning Officer in Dublin Castle, who announced the overall result.
A referendum in Ireland proposing the country's ratification of the Treaty of Lisbon  has been rejected by the electorate despite near universal support from the country's political establishment. 

Although in most states the issue has been (or will be) decided through parliamentary vote, Ireland was obliged to hold a referendum by its constitution. Ireland is the first state to reject the treaty which came about as a reworking of the E.U. Constitution, rejected by referenda in France and the Netherlands in 2005.

862,415 cast their vote against the treaty and 752,451 people voted for it, yielding a 53.4% to 46.6% margin of defeat. All 43 constituencies have been counted.

"It looks like this will be a No vote," Dermot Ahern, the Irish Minister for Justice said on live television. "At the end of the day, for a myriad of reasons, the people have spoken."

"The Treaty is not dead," said European Commission President José Manuel Barroso. "The ratification process is made up of 27 national processes, 18 Member States have already approved the Treaty, and the European Commission believes that the remaining ratifications should continue to take their course," he said.

"Ireland remains committed to a strong Europe," said Barroso after speaking with Taoiseach (prime minister) Brian Cowen. "Ratifications should continue to take their course."

France and Germany issued a joint statement expressing regret over the result. The United Kingdom said it would continue with its own ratification process.