A Fine Gael councillor died after he had a heart attack at his polling station in Co Monaghan yesterday.
Monaghan County Councillor Owen Bannigan, who was expected to top the poll, died on the way to hospital.
Mr Brannigan, a farmer, had been a councillor for 15 years.
A by-election will have to be held to fill his seat.
The Republic went to the polls yesterday in european and local government elections.
Voters choose 11 representatives to the european parliament and 949 seats on county councils around the country.
Dail by-elections were also held for Longford/Westmeath and Dublin West. The turnout was reported to be slow but steady. Counting for the local and by-elections will begin this morning while the tally of ballots for the european elections start on Sunday.