There are a lot of happy faces.
At Dublin Castle, Sinn Fein president Mary Lou McDonald and deputy leader Michelle O'Neill held up a banner with the words: "The North is next".
The referendum will decide whether the eighth amendment of the constitution is repealed or stays in place.
Since 1983, around 170,000 Irish women have gone overseas for terminations.
When Prime Minister Leo Varadkar arrived, he struggled to make his way through celebrating crowds before telling them the referendum had been a quiet revolution for a modern Ireland.
Polls close at 10 p.m., with results expected to be announced Saturday evening.
Opponents of the repeal movement have conceded they have no chance of victory.
Standing nearly back to back, one held a "Yes" leaflet high, saying, "Your body, your vote, your choice", while another said: "Please vote No - thousands of lives depend on it".
A survey released five days prior to the referendum showed that 56 percent of the people would vote Yes, 27 percent would vote No, 14 percent say they don't know while three percent would refuse to answer. "That would be wrong".
PHL eyeing oil from non-Opec countries
The group previously agreed to curb their output by about 1.8 million barrels per day to boost oil prices and clear a supply glut. For Russia, stability is more important than a short-term significant growth in price, he said in the interview.
The Irish Times and RTE television exit polls suggest the Irish people have voted by almost 70 per cent to repeal the 1983 constitutional amendment, which requires authorities to treat a foetus and its mother as equals under the law.
The decisive outcome of the landmark referendum was cast as a historic victory for women's rights.
Irish citizens living overseas who want to participate in the country's abortion referendum are flying home to cast their vote - with some even offering to pay others' travel costs.
The topic is considered one of the most divisive and hard subjects in public life, and has prompted posters with graphic post-abortion scenes on the streets of Dublin, erected by the No camp.
Katherine Zappone said Saturday she is confident new abortion legislation can be approved by parliament and put in place before the end of the year.
May's minority Conservative government relies on support from MPs from Northern Ireland's Democratic Unionist Party for a majority in the British parliament - and the Protestant DUP strongly opposes abortion law reform.
It said: "The government has made it clear, if the Eighth Amendment is repealed, it intends to introduce new legislation, including permitting unrestricted abortion during the first 12 weeks of pregnancy".
Donohue needed to travel to Britain to have an abortion when her baby diagnosed with a fetal anomaly.
"If we vote Yes on Friday we'll wake up to a country on Saturday that is the same country with the same decent people, but just with laws that can be more caring and more compassionate".
Campaigns on both sides of the issue grew intense leading up to the vote.
Still, just before slipping his vote into the ballot box, he said, he whispered a prayer for victims of rape and incest, who, had the "yes" vote been rejected, would be barred from having an abortion.
Backing for repeal was highest among young voters, including many who returned from jobs or universities in continental Europe to vote, but was also high among every age group except those 65 or older.