Irish Prime Minister Leo Varadkar says the country has voted resoundingly Yes to liberalise its strict abortion laws.
Varadkar claimed Ireland was united - with men and women, nearly every age group and every social class opting for reform in Friday's referendum.
He campaigned for the change, which he said represented the compassionate choice for women forced to travel to England for terminations or taking unregulated abortion pills.
"The public have spoken, the result appears to be resounding in favour of repealing the Eighth Amendment, possibly to carry every constituency in the country," Varadkar said on Saturday.
With polling data suggesting seven out of 10 voters backed reform, campaigners in favour suggested it meant a moment of profound change - when the nation had collectively stood up for women and their healthcare.
The vote saw citizens effectively opt to either retain or repeal the Eighth Amendment of the state's constitution, which prohibits terminations unless a mother's life is in danger.
Earlier, the No campaigners conceded defeat.
The Save the Eighth group said: "What Irish voters did yesterday is a tragedy of historic proportions.
"However, a wrong does not become right simply because a majority support it."
One poll by national broadcaster RTE suggested around 70 per cent of the electorate have voted to end the country's all but blanket ban on terminations, with another, by The Irish Times, recording 68 per cent in favour of ditching the prohibition.
While the official result is not due until later on Saturday, it appears Ireland is on the cusp of a defining moment in its social history.
The Together For Yes organisation said: "This is a vote for dignity and decency.
"If exit polls are reflected in the official vote count later today, this will be a moment of profound change in Ireland's social history, a moment when the nation collectively stood up for women and for their healthcare, and voted for constitutional change."
Reacting to the exit polls on Friday night, Taoiseach Leo Varadkar, a vocal proponent of liberalisation, tweeted: "It's looking like we will make history tomorrow."
Thousands of Irish citizens living overseas travelled home in droves to exercise their democratic right on the emotive issue.
The specific question people were asked was whether they wanted to see the Eighth Amendment replaced with wording in the constitution that would hand politicians the responsibility to set future laws on abortion, unhindered by constitutional strictures.
If the Yes vote is confirmed, the Irish Government intends to legislate by the end of the year to make it relatively easy for a woman to obtain the procedure in early pregnancy.
Ministers have promised to allow terminations within the first 12 weeks, subject to medical advice and a cooling-off period, and between 12 and 24 weeks in exceptional circumstances.
A total of 3.3 million citizens were registered to vote in Friday's referendum.
Australian Associated Press