More than 430,000 people are entitled to vote across Cork city and county.
Polling stations opened their doors at 7am, and won't close until 10pm this evening.
Polls will remain open until 10pm tonight with voters being reminded to bring valid ID and only write numbers on the ballot paper.
Chief Executive of the Electoral Commission, Art O'Leary, says don't worry if you make a mistake on the ballot paper:
"When you're voting, you make a mistake on the ballot paper, then you can just bring it back to the person who gave you the ballot paper, say you've made a mistake, they'll destroy it, and you'll be given a fresh ballot paper.
There is no shame in this. Don't be embarrassed. It's much more important that you vote properly than you spoil your vote."
