Paul Struthers is stepping down as chief executive of the Professional Jockeys Association after close to 10 years in the role, citing the toll the job had taken on his family and personal life.
The news comes 12 days after the conclusion of the disciplinary hearing involving Bryony Frost and Robbie Dunne after which the PJA's leadership was criticized for its handling of the case.
The PJA, whose board said it had "reluctantly agreed" to Struthers' request to step down, has appointed Dale Gibson to act as interim chief executive.
Struthers said: "Throughout my time at the PJA, I have been extremely fortunate to represent jockeys who I have nothing but complete admiration for. In my dealings with hundreds of jockeys over the years, I have learned a huge amount from them and have tried to treat everyone with sincerity, respect, and decency.
"Due to the relentless nature of their lives, jockeys rightly need the PJA to be available at all times and this role is a way of life, not a job. As many in racing will empathize, this has taken a significant toll on my family and personal life, and it is the right time to step aside."
Struthers succeeded Kevin Darley as PJA chief executive in 2012, having previously been head of communications at the British Horseracing Authority.
He added: "Representing the courageous, dedicated, and resilient men and women who make up our diverse membership has been the greatest privilege of my career.
"I would like to thank everyone that has supported me in my role and I am incredibly proud of what the PJA has achieved over the last 10 years. This is only possible thanks to a talented, hardworking team who share a passion for the job and an incredibly supportive membership.
"Finally, I am very confident that any recommendations and improved procedures that the PJA and the sport puts in place will serve all our members well and improve their lives. They deserve nothing less."
PJA chairman Jon Holmes said the organization understood and accepted Struthers' decision.
He added: "Paul has given a decade of his life to tirelessly striving to improve the lives of our jockeys. I and the whole team here want to pay tribute to Paul and thank him for everything he has done across a decade of selfless service."