Matt O’Connor is leaving his post as Leinster coach by « mutual agreement » after a disappointing campaign.
The Australian succeeded Joe Schmidt when he left for the Ireland job two years ago and won the 2014 Pro12 title.
But Leinster finished outside the play-off positions this season and forwards coach Leo Cullen will take temporary charge of the team.
« We set high standards for ourselves and for many reasons we did not achieve those highs, » said O’Connor, 44.
The former Leicester coach took the Irish province to the Heineken Cup quarter-finals in 2014 and European Champions Cup semi-finals this season.
A 25-20 extra-time defeat by champions Toulon last month was followed by the failure to make the Pro 12 play-offs.
« I am disappointed and frustrated with our form in the Pro12 this season, » O’Connor told the club website.
« However, the European journey that we took over two seasons, for a new group of coaches, players and staff, is one that we can be very proud of.
« The dynamic in Europe has changed with meritocracy and fewer teams competing and this has improved the quality.
« We went toe-to-toe with the best and there is no shame in losing to Toulon by the smallest of margins and I’m extremely proud of the group and the character shown. »
Leinster said on Thursday that the search for O’Connor’s replacement was under way.