Kevin Moore has immediately stood down as Bulldogs coach, and will be replaced by assistant Jim Dymock for the rest of the 2011 season.
Moore released a statement saying he made the decision after being told his services would not be required after 2011.
"Having considered the impact this will have on my family, my support staff and the players, and importantly, the club that I love and have been involved with since the early 1970’s, I will stand down effective immediately having helped the team complete its preparation for Friday night’s game against the Warriors in Auckland," Moore said.
"I feel very privileged to have been a part of a great club for so long and I want to thank all who have been a part of this journey with me."
The Bulldogs sit in 11th place on the NRL ladder, having lost seven of their past nine matches.
"Kev has been great for our club over a forty year period across a number of roles, from ball boy to head coach. However with regard to the head coaching position it had become clear that it was time for a change," Bulldogs chief executive Todd Greenberg said.
"It’s an incredibly hard position for us all to be in given Kev’s standing within the club and we are certain his contribution over a lifetime – not just his time as head coach – will be given due recognition by all Bulldogs supporters," Greenberg said.
"Kev should be commended for making what is an incredibly tough decision for him professionally and personally.
"He was a major part in the club’s turnaround over the past three years both on and off the field and his contribution will be remembered fondly by all those who have worked with him.
"Kev can be proud of his achievements as head coach – his Dally M coach of the year title in 2009 being paramount among them.
"Furthermore, his lifelong dedication to the club is to be respected and admired and no matter where he goes or what he does in the future, he will always be a Bulldog.
"He can leave with his head held high and we thank him for his service and dedication to the club."