He admitted his time as Housing Minister was the most challenging he faced during his career in politics.
Some in Fine Gael HQ are not completely surprised at the move, feeling Eoghan Murphy had lost his love for politics during that difficult time in housing.
The move sets up an intriguing by-election in Dublin Bay South.
The vote will likely be held towards the end of November and former TD Kate O'Connell emerges immediately as a serious candidate.
All eyes will also be on the Green Party's Hazel Chu, who's a councillor in the area, a constituency that's also home to her party leader Eamon Ryan.