Jim Mallinder has been sacked as Northampton director of rugby after ten years at the helm
Saints chairman John White said "the board and major shareholders felt that the time was right for some change," in a statement released by the Aviva Premiership oufit.
Former England full-back Mallinder was the Premiership's longest-serving rugby director, having taken over at Franklin's Gardens in 2007.
Northampton currently lie 10th in the Premiership, having won just four league games all season, while they prop up their European Champions Cup pool following three successive losses.
The final straw appears to have been last Saturday's 43-32 European home defeat against the Ospreys, while Saints have also twice shipped more than 50 points to Saracens this term.
The club said Northampton attack coach Alan Dickens will take over in a short-term position of interim head coach until a replacement is found for Mallinder.
In a statement, Saints said: "Northampton Saints can confirm that director of rugby Jim Mallinder will be leaving his position at the club with immediate effect.
"Having taken the reins at Franklin's Gardens in 2007, Mallinder was the longest-serving director of rugby in the Aviva Premiership, but due to the recent string of results the Saints board agreed that a change in management was in the best interest of the club."
💬 "The decision was not taken lightly.— Northampton Saints (@SaintsRugby) December 12, 2017
"Jim has been an outstanding director of rugby. We have been very lucky to have him and he will always be a part of the Saints family."
Saints chairman John White comments on the departure of Jim Mallinder pic.twitter.com/YEcnHChsuI
White added: "Jim has been an outstanding director of rugby. We have been very lucky to have him at Franklin's Gardens, and he will always be a part of the Saints family.
"This is not a decision that has been taken lightly, but the board and major shareholders felt that the time was right for some change."
Mallinder guided Northampton to the Premiership title in 2014, while Saints were beaten European Cup finalists three years earlier. Northampton also won the European Challenge Cup and Anglo-Welsh Cup under his direction.
Northampton chief executive Mark Darbon said: "Jim has done a superb job as Northampton Saints' director of rugby over the last decade, and the amount of silverware the club has won during his tenure speaks for itself.
"We thank Jim for all he has done at Franklin's Gardens.
"We will now begin an extensive search to find a world-class director of rugby to replace Jim.
"While that search is under way, we will look to bolster our existing coaching group with some additional leadership and experience on a short-term basis for this season.
"Alan Dickens will oversee rugby and coaching matters on a temporary basis as interim head coach."
Saints face a return fixture against the Ospreys in Swansea next Sunday, which is followed by successive Premiership appointments with champions Exeter, Harlequins and Gloucester.
Halifax-born Mallinder, 51, won two England caps on the 1997 tour of Argentina and had a lengthy playing career with Sale. He also coached Sale and England Saxons before linking up with Saints 10 years ago.