The BBC says the yes side seems to be winning.
Government ministers have said they believe it will pass, while prominent “no” campaigners have conceded defeat.
Counting started at 09:00 BST on Saturday morning. An “unusually high” turnout has been reported.
A result is expected late afternoon on Saturday.
The Indy says the no side has conceded.
The Republic of Ireland appears set to become the first country to introduce same-sex marriage by a popular vote, especially now since the ‘no’ campaign appears to have conceded.
David Quinn, of the Iona Institute and ‘No’ campaign tweeted a concession and congratulations to the ‘Yes’ campaign amid widespread reports of a landslide.
A landslide!
Congratulations Ireland!