People are queuing to get into the square of Dublin Castle to witness the referendum result later.
The decision will be broadcast on a large screen to approximately 2,000 people.
Mothers and Fathers Matter, a group which campaigned for a No vote, said: “From our point of view, we have represented a proportionate of the population greater than those who support any political party
“One in three Irish people in this campaign was not represented by the political establishment, the media or the institutions of the state.
“We are proud to have fought on behalf of those voices when nobody else would.”
"Today’s result was achieved by the Government after they issued certain promises about surrogacy, adoption, and a range of other issues. A lot of voters believed those assurances and they must now be kept.
"Once again, we offer our congratulations to the YES side on a hard won victory. This is their day, and they should enjoy it”.