The overall vote turnout to elect Ireland's ninth president is understood to have been just under 50% when polls closed tonight.
Early figures put the percentage vote somewhere in the mid-20s but a small surge in the evening boosted the overall turnout nationwide.
Many regions experienced lower-than-average interest throughout the day despite the record seven candidates in the race.
Opinion poll topper Sean Gallagher, dogged by controversy over his political fundraising past and financial transactions in his businesses, voted early at Blackrock National School in Dundalk, Co Louth, with his wife, Trish.
Labour's Michael D Higgins cast his ballot with his wife, Sabina Coyne, and their sons, Daniel and Michael Jnr, in Bushy Park National School, Galway city, while Gay Mitchell voted at Kildare Place Primary School, Upper Rathmines Road, south Dublin.
Senator David Norris voted at Marlborough Street in the north of the city, a walk from his home, Mary Davis at Burrow School, Howth Road, Sutton, also north Dublin, and Dana Rosemary Scallon near her home in Claregalway, Co Galway.
Sinn Féin's Martin McGuinness, who stepped down as the North's Deputy First Minister to run, has no vote in the Republic but accompanied party colleague, Donegal South West TD Pearse Doherty, as he voted in Bunbeg, Co Donegal.
Indications from polling stations nationwide suggested that turnout would be nowhere near the high 70% seen at the February General Election.
Results from the first counts in the 43 constituencies are expected early tomorrow evening or, depending on the final turnout, later tomorrow night.
While a formal declaration by the Presidential Returning Officer is not expected until Saturday, the voting pattern should be clear much earlier and the final outcome known late tomorrow.
Joe Costello, director of elections for Mr Higgins, urged voters to get out and exercise their right.
"The next president will play a crucial role in restoring morale and confidence in Ireland, and rebuilding our reputation abroad," he said.
"I am absolutely confident that Michael D Higgins is the right person for the job. With his unrivalled diplomacy skills and vision, Michael D will be a president we can all be proud of."
Mr Gallagher, with his "secret weapon" wife in Blackrock, said there is a desire for new politics in Ireland.
"We have run a clean, positive campaign which has resonated with people in every part of the country, in every sector and every age group," he said.
Mr Gallagher said he never had any second thoughts about running but would not be drawn on whether a career in politics beckons if the tilt at the presidency fails.
"It's been a tough 72 hours but it's unfortunate what the campaign ended being about in the last couple of days," he said.
"I'm going to take one step at a time. I think we have plenty to focus on in the next 48 hours and I think one campaign at a time is enough, thanks."
Mr McGuinness said he hoped people would use their vote to deliver political change.
"Many people have yet to vote," he said.
"I would encourage each and every person with a vote to use it. This is your chance to usher in change in Ireland."
About 3.1 million people were eligible to vote in the single transferable vote system, where the successful candidate needs 50% of the vote plus one.
Ireland's ninth president follows the respected two terms, totalling 14 years, of Mary McAleese. She leaves office on November 10 after a remarkable tenure marked by her "Building Bridges" theme and work on the peace process in the North.
The president's residence, Áras an Uachtaráin in Dublin's Phoenix Park, was also opened to more guests and visitors than ever before.
Counting of ballots begins at 9am tomorrow in 43 constituencies across the country with results relayed to a central database in Dublin Castle.
If the pattern of opinion polls in the final week stands up to the test, no candidate is likely to be within 10% of the 50% plus one majority.
The electorate is also being asked to vote on two referendums to make alterations to the Irish constitution.
One is on a proposal to beef up the powers of parliamentary committees in holding inquiries into matters of public interest, while the other would allow the Government to reduce the pay of judges.
Also, in west Dublin, voting takes place to fill the seat of late former finance minister Brian Lenihan.