Counting of votes in the Donegal South West by-election began at 9am.
Five candidates are competing to fill the Dáil seat vacated by Pat 'The Cope' Gallagher when he was elected to the European Parliament in June of last year.
Traditionally, Donegal South West has been a Fianna Fáil stronghold, with the party returning two TDs in the 2007 election.
However, the political landscape is very different now and recent polls indicate Sinn Féin will perform well.
There was a 66% turnout in this constituency in the last General Election.
Yesterday's turnout is being estimated at 53-55%, but official figures will not emerge until later today.
The five candidates are Sinn Féin's Pearse Doherty, Fine Gael's Barry O'Neill, Fianna Fáil's Brian Ó Domhnaill, Independent Thomas Pringle and Labour's Frank McBrearty.
Despite tallies indicating Pearse Doherty is polling well, the Sinn Féin Senator is taking nothing for granted.
A joint tally between parties is being conducted, by lunchtime it will paint a clear picture of how this election is likely to go.
Pearse Doherty is the hot favourite to take the seat, after winning a legal challenge in the High Court forcing the Government to call this by-election.
Independent candidate Ann Sweeney withdrew from the vote but her name remained on the ballot.
Counting of votes is taking place in the Finn Valley Centre in Stranorlar, with a result expected sometime late this afternoon or early this evening.
