Former foreign affairs minister Micheal Martin has been elected as the new and eighth leader of Fianna Fail.
The Cork TD was the front-runner in the race after Taoiseach Brian Cowen revealed his intention to stand down.
Finance Minister Brian Lenihan, Social Protection and Defence Minister Eamon O Cuiv, and Tourism Minister Mary Hanafin also put themselves forward in the contest.
The leadership battle was decided by a secret ballot, using proportional representation.
In the first count, Mr Martin received 33 votes, Mr O Cuiv received 15, Mr Lenihan got 14 and Ms Hanafin was eliminated with 10 votes.
After transfers in the second count, Mr O Cuiv and Mr Lenihan were on 18 votes each and Mr Martin 36 votes.
On the final count, Mr O Cuiv was on 22 votes and Mr Martin won with 50 votes.
Taoiseach Brian Cowen addressed the meeting at the beginning for around 10 minutes.