Counting has begun of votes that will determine whether Government plans to enshrine children's rights in the constitution should be accepted.
The first indications of the outcome should be known before lunchtime, unless the vote is split by a narrow margin.
Reports last night suggested a voter turnout of around 30%, in what was only the second referendum ever to be held on a Saturday.
Counting of votes from the 43 constituencies started at 9am.
Results will be fed through to the Referendum Returning Officer Riona Ni Fhlanghaile at Dublin Castle.
Polls opened yesterday morning on the back of a potentially damaging Supreme Court ruling over the misuse of public funds to inform the electorate of the campaign.
Despite the legal setback, Justice Minister Alan Shatter insisted he was confident the public would vote in favour of the reforms to ensure Ireland's children receive the utmost protection.
The court said public funds cannot be used to promote a vote one way or another.
It ruled that the Government's use of public funds had been wrong and that extensive passages on information leaflets had breached rules of fairness.
The proposed new Article 42a would see children's rights for the first time recognised in Ireland's constitution to ensure their protection.
If passed, reforms will allow for state intervention if parents neglect or fail in their duties to their children - regardless of whether they are married.
A child's views could also be taken into account during child protection proceedings if the reforms come into place.
Changes would also see a child eligible for adoption where their parents have been found to have failed them and in some cases, parents would be able to voluntarily put their child up for adoption.
And all custody, guardianship and adoption of children would be based on the child's best interests - if the public has voted 'Yes' in the referendum.
All political parties - both in Government and Opposition - have campaigned for a 'Yes' vote.
But five TDs wrote to the Government on the back of the Supreme Court ruling urging that the vote be delayed.
Others supporting a 'Yes' vote include leading children's charities the ISPCC, Barnardo's, the Children's Rights Alliance and lobby group Campaign for Children.
Retired Supreme Court judge Catherine McGuinness, who was the first to call for a children's rights referendum after the notorious Kilkenny incest case in 1993, also campaigned.
The 'No' camp includes former MEPs Kathy Sinnott and Dana Rosemary Scallon, the Parents for Children Group and journalist John Waters, who has campaigned for the rights of fathers.