"It's been a privilege to lead the organisation that Billie Jean King founded and to have worked with the world's best female athletes, dedicated tournament promoters and passionate and professional WTA team members," Allaster, who joined the WTA as its president in 2006, said in a statement.
"For 25 years I have dedicated my professional life to the sport and I'm proud of the work I leave behind."
The WTA said the process to replace Allaster is underway but offered no timetable for when a successor will be named.
During her tenure, Allaster secured a record number of new sponsors, enhanced the health and well-being of athletes through her work in streamlining the tennis calendar and saw a jump in TV viewership and attendance at the sport's biggest events.
The Canadian, who was named as one most powerful women in sports in 2009 by Forbes, said she was leaving her position for personal reasons to spend more time with her family and called the recent death of her brother-in-law and the ATP chief executive Brad Drewett as a "personal wake-up call."
“The recent loss of my brother-in-law and the ATP's CEO, Brad Drewett, has provided a personal wake-up call about life, family and priorities and it is time for me to shift some time and energy that way," said Allaster, whose departure takes effect on Oct. 2.
"When I joined the WTA my goal was to leave the organisation on a stronger footing and I feel a humble sense of pride in what we have all accomplished here.
"I have focused on what it means to be a champion and I have tried to be a strong role model for women to encourage success in the sports industry."
(Reporting by Steve Keating in Richmond, Virginia; Editing by Frank Pingue)
Share
