London - Conor O'Shea will step down as director of rugby at Harlequins at the end of the current English Premiership season, he announced on Wednesday.
The former Ireland full-back, 45, has been at Harlequins since 2010 and guided the London club to glory in the English Premiership for the first time in their history in 2012.
They have also lifted the European Challenge Cup and the Anglo-Welsh Cup during his time at the helm.
"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 told the club's official website.
"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."
Quins are currently third in the Premiership table and have already reached the quarter-finals of the Challenge Cup, ahead of Friday's sixth and final pool game away to Montpellier.
"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," O'Shea added.
"I will say my goodbyes when the season is over."
Chief executive David Ellis said: "All of us at the club are of course disappointed that Conor will be leaving us at the end of this season.
"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.
"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."