An exit poll published on Friday night (Ireland time) indicated that Ireland had voted by a landslide to reform its tough abortion laws.
According to the Irish Times projection, 68 per cent voted Yes to scrapping the country's de facto ban on abortion.
Voters were asked whether to scrap the eighth amendment of the Irish constitution, which puts the life of a mother and her baby on equal footing. The amendment was introduced via a referendum in 1983.
The current regime forces thousand of women to travel to England for terminations, which the pro-choice Yes campaign says is inhumane and causes needless suffering in an already traumatic situation.
Polls previously suggested that the Yes camp had a comfortable majority, but in the wake of the Brexit vote and the surprise victory of Donald Trump, the result seemed close to call.
Yes campaign: It's time for more compassionate law
Ireland has some of the toughest abortion laws in Europe, banning the procedure in cases of rape, incest or fatal foetal abnormalities. Those who choose to have an illegal abortion in Ireland risk up to 14 years in prison.
But the pro-life No campaign says the alternative proposed by the government goes too far, as it would allow unrestricted access to abortion for up to 12 weeks.
Leo Varadkar, the Irish prime minister, said repealing the eighth amendment would pave the way for more compassionate abortion laws.
"I hope that a Yes vote will help to lift that stigma and help to take away that legacy of shame that exists in our society," Mr Varadkar said.
No campaign: Proposed replacement is too extreme
However, speaking to the Telegraph, No campaign chief John McGuirk said it was essential that Ireland protected the eighth amendment or it would put the lives of countless unborn children at risk.
"If you believe a child has rights before it is born then this referendum would take away those rights," Mr McGuirk said.
It came as GPs supporting the No side claimed that asking doctors to carry out abortions without a reason being offered cannot be described as healthcare.
General practitioners opposed to the repeal of the eighth amendment said the proposals to liberalise Ireland's termination laws would amount to "abortion on demand".
More than 120 GPs put their names to the open letter, expressing "serious concerns" about health minister Simon Harris's plan.
Dr Brendan Crowley, one of the signatories, said the doctors were "not expressing a position on abortion one way or the other".
"However, we are united in the view that the Government's proposals would open the door to abortion on demand in a similar manner to that prevailing in Britain," he said.
"In circumstances where the draft abortion law specifies that the role of the GP will be 'carrying out the termination of pregnancy' at the request of the patient, without the need for any reason to be given by the patient, there is no way such a proposal could be described as 'healthcare'."
Thousands return home to vote
Thousands of Irish voters have flown home from as far away as America, Vietnam and Kenya to have their say in the referendum.
Ciaran Gaffney, based in Buenos Aires, Argentina, spotted four of his countrymen on a plane home to vote.
He tweeted: "Was actually so humbled and relieved to meet four other Irish people on the flight from Buenos Aires to London, all of them flying onwards to Dublin today or tomorrow to #voteyes."
Mary Galvin, 73, from Wexford, cut her holiday to Italy short by a day to be home for the referendum to vote No.
She said: "I've been a nurse all my life - the hard cases, there are many hard cases, like a lady who had been raped, and you help deal with that and the aftermath of that, with support."