O'Shea to walk out on Quins
Since joining Harlequins in March 2010, Conor has overseen the club's most successful period in the professional era winning the European Challenge Cup in 2011, the Premiership in 2012 and the LV Cup in 2013.
In addition, he has championed the role of the club's Academy, in the process bringing through a wealth of talented players to the national and international stage.
"I will have been very fortunate to have had the opportunity to contribute to this special club for over six years come May," O'Shea said.
"I have enjoyed working with everybody at Harlequins, from the players to the staff to the supporters, having said that, the end of this season is the right time for me to move on.
"We have a very talented group of players and coaches who are intent on securing silverware this season and that is my sole focus and where all our efforts are concentrated. I will say my goodbyes when the season is over."
Commenting on the announcement David Ellis, the club's Chief Executive said: "All of us at the club are of course disappointed that Conor will be leaving us at the end of this season.
"Conor took over as Director of Rugby after a difficult period in our history. Under his leadership and through his determination, energy and positive approach he has helped restore pride in our famous shirt and rejuvenate the playing style for which we are known.
"His passion for the game, for the club and for the squad he has built is there for all to see.
"On behalf of all of us associated with Harlequins I would like to thank Conor for his tireless and selfless commitment over the last six years, guiding us through our most successful period on the field.
"Conor will leave the club in a significantly better place than he found us and for that we are all grateful to him.
"We all wish him and his family good fortune and every success in the future; there will always be a warm welcome for Conor at The Stoop."
The club, helped by its resources and rugby expertise, will immediately begin the process of finding a new Director of Rugby, one that is best suited to taking the squad forward.
No further announcements will be made until a new Director of Rugby has been appointed.
