The President has accepted the resignation of Minister for Defence Willie O'Dea.
In a letter to the Taoiseach, the minister said he had come to the conclusion that his continuing in office would distract from the important and vital work of the Government.
Mr O'Dea said he was privileged to serve in the Government for the past five-and-a-half years and said his record as minister had been to the benefit of the Defence Forces and the Government.
In reply, Taoiseach Brian Cowen thanked the former minister for his hard work and commitment.
Responsibility for the Department of Defence has now been assigned to the Taoiseach.
Last summer, Minister O'Dea made a sworn statement in connection with a High Court case taken by Sinn Féin local election candidate Maurice Quinlivan.
While he accepted making comments about Mr Quinlivan which were published in a local newspaper, he denied making other, unpublished, comments which figured in the court case.
It later transpired that he had in fact made the comments - Mr O'Dea said he had forgotten making them, and apologised.
The Dáil was suspended this morning following rowdy exchanges over the issue, despite the Government winning a confidence motion in Mr O'Dea last night.
In an interview this afternoon with RTÉ News, Mr O'Dea denied the Fine Gael accusation that he had committed perjury.
Asked about his statement that he received information from An Garda Síochána, Mr O'Dea said 'It was just general chit chat,' 'I passed it on - I shouldn't have passed it on.'
'I have made a bad mistake, I've paid heavily for it, I am sorry, I am contrite, I've apologised, I apologised again ... I don't know what else I can do.'
'I say things that I don't really mean sometimes in the heat of battle.'
A review of Willie O'Dea's political career to date