Polling station staff are saying a "steady stream of voters" mean it is likely turn-out will be high as people vote in two referendums today.
About 9% of voters had turned out by 10am in Kildare, while in Cork it was close to 10% in some polling stations. Tipperary has seen voter turn-out of 8% so far.
Newstalk reporter Jonathan Healy said the strong early vote may indicate that overall turnout could be high, with some polling station staff telling him it looked like a general election turn-out rather than a traditionally lower referendum one.
Polling stations opened at 7am today - some saw queues at that time - and will remain open until 10pm tonight.
Update 11.30am: In the midlands, turn-out at six polling stations in Laois is averaging 6.3%. The figure a short time ago in Offaly was 5.9%. And in Westmeath, it's averaging 5% at two polling stations.