Another poll by national broadcaster RTE suggested an even bigger victory, with 69 percent to 30 percent backing reforms.
Yet the exit poll showed overwhelming majorities in all age groups under 65 voted for change, including nearly nine in every 10 voters under the age of 24.
Ireland votes on Friday in an abortion referendum that could be a milestone on a path of change in a country that, only a few decades ago, was one of Europe's most socially conservative. According to several exit polls, it looks as if pro-abortion forces have decisively delivered enough votes to overturn the country's 8th amendment that bans abortion.
In case you're not familiar with what's been going on, the Irish Twittersphere have been cataloguing their journeys home to Ireland to repeal the eighth amendment.
"It's an added bonus that I get to see my family, but the referendum is the only reason I came back to be honest", she said.
"I did a little volunteering to canvas, and when you go out to houses, talk to people, they really tell you their mixed opinions, so there's very complex views and I think it could be quite close".
Members of the public vote in Ireland's abortion referendum at Scoil Thomas Lodge polling station on May 25, 2018 in Dublin, Ireland.
Earlier Taoiseach Leo Varadkar, a proponent of liberalising Ireland's strict abortion regime, predicted a high turnout would be good for those campaigning for change. The country's deputy prime minister, Simon Coveney, said, "Thank you to everybody who voted today - democracy can be so powerful on days like today - looks like a stunning result that will bring about a fundamental change for the better".
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Theresa Sweeney, a repeal supporter, was one of the first people to arrive at the North Grand Church polling station in Dublin.
Campaigning was not allowed on Friday, but Dublin was still filled with signs and banners urging citizens to vote "yes" or "no". The consequent prohibition on abortion was partly lifted in 2013 for cases where the mother's life is in danger.
The Ireland abortion referendum exit poll results will be announced on the Irish talk show The Late Late Show and RTÉ's David McCullagh will reveal what the people interviewed after they voted for or against repealing the Eighth Amendment.
The official referendum vote count isn't expected to be completed until Saturday afternoon local time. He said, "I'm a staunch No". "It's a vote as to whether we trust the women of Ireland to make decisions about their own lives for themselves".
"Whether they vote in large enough numbers to help us win the referendum is an open question", he said.
As per 1983 amendment, anyone terminating a pregnancy in Ireland could face 14 years in jail.
If the Eighth Amendment, also known as Article 40.3.3, is repealed, it is expected to be recommended that abortions in the first 12 weeks of pregnancy be introduced without restriction.
The ban has led to thousands of women travelling each year to neighbouring Britain, where terminations are legal, or increasingly turning to abortion pills sold online. They correctly perceived that Ireland was gradually becoming a more secular country, and wanted to create a bulwark against the introduction of abortion that would be hard to reverse.